Anyone used Sworkit? I've just come across it and I like the look of it. I got a lot out of doing circuit training with an instructor ahead of my triathlon last year, and an app would be a good way to replicate the structure and motivation you get from an instructor - not as good, obviously, but a darn sight cheaper.
Available for iPhone and android in free and 69p "pro" versions.
http://www.sworkit.com/
