If you're looking for just another free app for your phone, you might try Cyclemeter. I used to use something called "A Route Tracker," but I'm not sure why I stopped several years ago.
I rarely look at the phone while I'm riding. I once put it on the handlebar with some kind of mount, but I felt it was just way too much abuse for the phone. Probably just needed a better mount. I just keep the phone in my jersey pocket and look at it when I'm done and record the stats.
Cyclemeter occasionally tells me that I topped 40 mph or something when I'm pretty sure I didn't, but I feel it's good enough for my tracking purposes. I like to see my average speed go up over the course of the year.