The crumpler ones are pretty good too. Have a double velcro strap (ie one strap velcros down and is secured by another) which is secure and means there is no exposed velcro. They're made of stretchy neoprene to keep your phone warm if you go scuba diving and provide a bit of cushioning and they have a little stash pocket on the flap that covers the phone. They also have a slightly lame plastic logo stiched onto them that can be removed with a knife.
Overall I think they're a good way to overcome the difficult manoevure of taking a phone out of your trouser pocket when you can't stop pedalling. This led to me dropping my phone too many times.
edit: here's a link
http://www.mymemory.co.uk/memory/Cru.../Bag/70/-/Blue