I am having this problem as well.
I have less than 10 pictures stored on my phone. No videos. 1.9G of music. 24 apps totaling 1.3G.
I already went through all my contacts and made sure they weren't accidently doubled up and hidden under "linked contacts".
I went through my Safari and cleared the history and reading list.
I deleted all of my recent calls and text messages.
I also regularly go through my email and delete everything.
Yet I still have 2.9G of other.
I have restored my phone multiple times, but that only brifely fixes the problem.
Normally I wouldn't care, but I am stuck with an 8G phone for another year, so having almost 3G of storage used up by "other" is extremely frusturating.
Someone, PLEASE help me with this.