How do I clear data listed as "Other" on my iPhone?
I cleared 2gb of "other" space by using DiskAid to dig into the file system of the phone and clear out corrupted data. 

WARNING - this may be dangerous, use extreme caution. If in doubt, don't.

Once diskaid is installed and running, click the file system menu on the left to expand the folders on the right. When looking around, I found a 2gb file in applicationarchives related to a program that I know didn't download correctly, and had since been deleted. Removing the file freed up the "other" space.