When the button on my Nike Fuelband broke, I eventually decided to get a Pebble and run the Misfit app on it to track steps. I've also loaded Tetris onto it and the Swarm check-in app. I also get notifications from my phone, via bluetooth.
With a little bit of C, it also seems quite easy to create your own apps or watch faces:

Thus far, enjoying my pebble... I'm sure you'll get a lot more out of it, though -have fun!
Do you use the Misfit app?
I am not getting on well with it so far, which is annoying, given the main reason I bought the Pebble was an exercise tracker. :(
One night it thought I slept for 8.5 hours and walked 20,000 steps at the same time.. Perhaps I was sleepwalking?
But that aside, the step count / points count seems quite inaccurate and for me does not seem to match their indications of what would be required to get the step counts. I guess I had got used to the Nike Fuelband, so perhaps it will just take me time to get used to this.