Q: Do you guys know of any good biking apps for the iPhone? I really like the Nike+ App for running, but that's all it does. Also, if you know a good bracket case for the phone, that'd be great, too. Thanks!

A: As far as apps go, we've had good luck with iMapMyRIDE ($2). It's pretty darn accurate, has a decent interface that's very similar to Nike+, and incorporates a social component into it. They have a free version available to try before you buy.
You can also give Runkeeper (Free) a go. It's a fitness app that tracks running, walking, and cycling, although we've run into a number of instances where it crashes for no reason, discouraging us from giving it a higher recommendation.
As far as brackets are concerned, you can pick up the Bracketron one pictured above for $40.
(Image: Aperturismo)

Commercial Flour Sa...
Runkeeper. LOVE IT. Paid version used to crash for no reason but not in the current version. I couldn't run without it and know people who bike with it.
Runkeeper hands down. HANDS DOWN!
best.app.EVAR!
I dig this app for cycling... Cyclemeter App
http://www.abvio.com/cyclemeter/
Bike Computer has always worked for me. Even uploads your tracks to EveryTrail.
MotionXGPS is really great. I also use runkeeper but I find that MotionX does a better job with pausing. Also, it has so, so, so many other great features (including cacheing maps) that it is worth the money. I often share the track with myself and upload it to the runkeeper site for record keeping.
Addendum: IIRC, Nike+'s technology is licensed from MotionXGPS
What about Biologic BikeBrain? It's free