The thing I can't understand is that the listed capacity of my touch is 7.27GB, so I figured that 730MB was the OS and stuff. I guess my Calendar info plus the size of the apps equals 105.5MB?
140 MB is nothing to worry about. The "other" is just part of the file system and can't be avoided. There have been cases of users (myself included) finding they had 2-5 GB of "other". That was a problem but the solution was simple - simply Restore the iPod.
You can try that. It won't hurt and it may clear up a couple of MB but I wouldn't expect miracles.