I'm looking at resetting my IDEOS to get rid of all the crap on it, so would anyone know what's in the internal storage of the phone? (asides from apps.) I'm just trying to work out what needs backed up.
The majority of internal storage is taken up by all the apps you've downloaded, and their app-specific data and caches. Most of this is fiddly to manage manually, and there's not much point trying to back it up (quite difficult without ADB, or rooting), or restore it for that matter.
If you've rooted your Ideos, you can back up everything with Titanium Backup... Use z4root (available somewhere, but not the Market) if you want to root it. Whatever's on your SD card ('cept for apps) stays there.
Just uninstall the crap you don't want manually I guess, or reinstall from the ground up. Alternatively, clear the data in select apps, I dunno. Some apps offer a settings backup (LauncherPro, Smart Keyboard Pro etc), and some have sync features (Contacts, Opera...)
Or try a custom ROM! Somwehere like here might be useful, if you're interested in ROMs, rooting, recovery and stuff.