How to clear the "Other" garbage files?

"Other" includes application data and other iPhone management data. If it grows that much, however, something got corrupted on your phone. The most common cause is interrupting a sync.

To recover the memory first try rebooting (hold HOME and SLEEP until an Apple logo appears, about 10 seconds. Ignore the "Slide to power off" message).

If this doesn't recover the space you will need to Restore the phone with iTunes.

Your media files sync from iTunes, so they should reload from iTunes. If you have purchased them on the phone and not synced them to iTunes this would be a good time to do it. ANY restore or upgrade can result in loss of data on the phone, so frequent syncs to iTunes are prudent.

Dennis,

Prior to restoring, I've resolved it by removing data from the phone.

This data can include music, movies, and/or Apps synced from iTunes (which should be in iTunes), or photos synced from your computer (not the camera roll photos but the photos that are on your computer that you sync). It is not limited to this and may be something else causing it.

Try removing them one at a time to see if it resolves the issue.

You may want to make sure all of your purchased content is transferred to your computer by going to File > Transfer Purchased From... (it may ask you to authorize your computer to which you should).

Hope this helps in resolving your issue.

Also, it is normal to see the other fluctuate some (ive seen my 16gb 3gs go from 200mb to 700mb during a sync)