Twitter released their free app for both the iPhone and iPad and it’s my favourite client by a long shot. As a matter of fact I haven’t had so much fun going through my Twitter feed since Tweetie on my Mac.

Well no wonder! They’ve both been written by Loren Birtcher, formerly of apebits the company which he formed to write Tweetie, amongst other software. Twitter bought Tweetie from apebits in April and Loren has been working with the team on an official app since then.

There have been lots of grumbles about the fact that it doesn’t have a unified timeline but that’s one of the reasons I prefer it over Twitteriffic. I like having my follows, mentions and DMs as separate timelines and the app keeps my position within those different views whenever I switch. The UI itself is fluid and very responsive. Tapping on a tweet with a link slides the web viewer over from the right and stacks it over the feed like so.

If a tweet contains a link to a video the app doesn’t lock the timeline and you can still scroll up and down the feed as it loads. The app has some other nifty gestures as well. Pinching any tweet will show the author’s profile and dragging an entry down will display the conversation associated with it.

Twitter for iPad and iPhone is free in the App Store.

PS Mobile has a nice simple interface with a menu bar in icon form at the top of the screen and undo/redo controls at the bottom, whether the iPhone is in Portrait or Landscape mode. The icons at the top perform image functions, exposure and saturation operations, filters and finally effects. The colour controls are quite intuitive, though not the most responsive. There’s a lag when you drag sideways to affect the saturation or exposure for example.

Here’s what the interface looks like.

As I mentioned earlier, it’s a nice simple interface and it’s simplified further when grading the photo. Here’s the saturation control which is increased or decreased by swiping across the screen.

And this is the colour tint interface.

Aside from the frequent performance lag I would’ve wished for more fine-grained controls as well as separate RGB curves. PS Mobile is a free download from the App Store.

A disclaimer first before I start on this app. I used to work at The Mill years ago. I often think of the place as my alma mater!

I wanted fine-grain controls and here they are! With Mill Colour photos can be graded by adjusting Lift, Gamma and Gain and each with individual RGB sliders. Actually, can I have slightly coarser-grain controls now? The sliders start at 1.0 and then increment up or down by .02 values. It would be a lot more useful to be able to adjust those increments.

In performance Mill Colour is everything that PS Mobile isn’t: the interface keeps up with you, doesn’t have any lag issues and looks clean and uncluttered.

As with PS Mobile, Mill Colour has a set of looks and in this app they feel more professional. To demonstrate the subtlety of some of the looks here are the Print and 70′s look.

There is one thing in the interface which is really distracting and not in the iPhone aesthetic: the horrible button feedback glow-flare.

Aside from the controls adjustments and the button feedback issue, the app is a joy to use. Mill Colour is a free app as well.

Amazon finally released a free iPhone app for the UK. Aside from searching for items as you would using a normal browser, this app has an interesting feature called Amazon Remembers. It will let you take a photo of an item you’re interested in, upload the photo and Amazon will try to find it for you. Yes, you read that right. Amazon will analyse the photo and match it to the items available for purchase.

Actually, that’s partly incorrect. The service doesn’t computationally analyse the photo, it uses Mechanical Turk to farm the job out to people who match the photo with items Amazon sells. Mechanical Turk is their online market place for people to carry out repetitive data-based menial jobs for a few cents per task.

When I tried the Remembers feature, the results came back within 15 minutes of the upload. I took a photo of our juicer and kettle and sent them off. The juicer was matched perfectly but it returned a coffee machine instead of the kettle. I’m sure the service will be refined and only improve over time.

It’s clear that Apple created a very compelling platform on which developers are using in inventive and brilliant ways.

After using Caffeine for a couple of hours I was hooked. It’s a free utility that stops your laptop from dimming the screen or going to sleep. How is this useful? How many times have you been watching something on YouTube for the screen to dim? Cue irritated push on the trackpad to get the brightness back.

Caffeine lives in your menu bar in the shape of a cup of coffee. When you want the display not to dim, click on the empty cup which changes to a full cup and et voilà, no more display dimming. When you’re not watching the screen anymore and listening to music whilst working, click on the full cup to drain it and revert the dimming back.

There are plenty of Sudoku games in the App Store but this one is a real “Look at what my iPhone can do!” game. You can photograph a game from a newspaper and Sudoku Grab (iTunes link) will digitise the puzzle… and then solve it for you. It will also let you email it to anyone who has a copy of the game installed on their iPhone.

The developer even posted how his application does it’s magic. Even though I don’t usually play Sudoku, this is enormous fun! Click on the images for larger versions.

Here’s how it look on different wallpapers on my Mac. Click for a larger view.

If you have an Airport Express you have to get Airfoil. The app lets you stream music from your Mac to just about anything that receives a wifi signal, including your iPhone, a Windows or Linux box or even the AppleTV. You select the source application and activate the destination speakers and off you go!

The Droste Effect is a technique whereby an image is rendered recursively to create a mind-bending (or brain-hurting) result. If you look at MC Escher‘s famous works you’ll see how a master artist uses this technique.

Now let’s have some fun. Download and install Adobe’s Pixel Blender Photoshop plugin, then get the Droste Effect Filter and start warping!

The effect is a lot more effective when it’s in motion. Take a look at OneInThree‘s fantastic video for Wild Beasts. I have to stress that the video was done mathematically by OneInThree themselves and not using the Adobe plugin. Enjoy!

Back in November I posted a quick review of one of my favorite iPhone apps, Weightbot. When the app was first released, the units of weight were either in kilos or pounds. I wanted an option for stones & pounds so I put in a request on the Tapbots support board, along with many other UK users. And they listened! A couple of point updates later, Weightbot had all three units.

I’m not 100% sure but I suspect this give the guys at Tapbots the idea for Convertbot. I bought the app just before our holiday in Bahrain to do quick currency conversions (even though there are free apps to do this). I wasn’t much surprised to see that the Bahraini Dinar wasn’t on the initial list of currencies. As before with Weightbot, I put in a request on the support site. As of version 1.1, the Bahraini Dinar is in the list!

Of course, Convertbot isn’t just a currency converter. It does length, mass, power, temperature, speed and lots more. The interface is very well thought out and nearly sublime. At £1.19 on the App Store, it’s well worth getting. Tapbots also have a free, stripped down version called Convertbot Mini.

Here’s a quick and handy tip if you want up-to-date exchange rates on the iPhone. The Stocks app lets you do that for free. All you have to do is add a new stock with both currencies three-letter codes like so:

GBPUSD=X

That’s it! You should get the current rate as well as a historical graph underneath.