I may have mentioned this iPad app before, but it is only recently that I started using it consistently in my practice. The app contains a variety of psychological tests and questionnaires. It has two versions - a free one and one costing $59.99. The difference is in the number and type of tests available within the app.
The free version has Depression Anxiety Stress Scales - both the 21 and 42 item version. I tend to use these on a regular basis to screen for and quantify any emotional problems. The scale is free, which makes it much more attractive than BDI and STAI-S, and is a nice tool for a screener. However, it tends to be a bit of a pain to score. Takes a bit of time, which I'd rather use for more enjoyable things. That's where the app comes in.
The electronic version is filled by the client on an iPad, and you receive an e-mail sending you to a secure website where the client's results wait all nice and scored. It all ends up being quicker and easier than scoring it by hand.
The app includes a number of scales, generally focusing on the clinical side of psychology, and is elegant and easy to use. I'd recommend it, even if you are going to just use the Depression Anxiety Stress Scales.