What's taking up all of this "Other" space on my iPhone?

Solution 1:

This space is taken by Application Metadata, and is also taken by Jailbreak applications since iTunes doesn't know that these are regular apps. Doing a full restore of your iPhone through iTunes should clear up this space. There aren't any utilities like DaisyDisk for iOS and the closest thing is iFile on Cydia, an application for managing the files on your device.

Solution 2:

I have found that there is a folder "var/mobile/media/applicationarchives" that strores zip versions of your apps when attempting to appsync to itunes. If there is an interruption, the file may not auto delete and still occupy the space. You simply ssh into that directory and delete. BAM!- you're good.