First, empty your trashcan.
See here for more information on clearing out the other space:
DaisyDisk is a viable alternative as well to Omnidisksweeper.
Do you have time machine on? If so, local backups can take up a fair amount of this 'other' space. You can use a terminal command below to disable local backups:
sudo tmutil disablelocal
This will not interfere with backups to your external harddrive. Just the local snapshot backups accumulated on your internal drive.
To remove media files you don't use, you can use finder to query each type of media, for example, see below. Search paramters for all .jpeg images:
Check your finder sidebar as well and search in your 'favorites' folders, such as Pictures. If you have your photos in iPhoto, you will need to delete the images in iPhoto directly. Then empty iPhoto's trash.
Delete any unused applications from your /Applications/ folder. Do the same with your ~/Pictures, ~/Movies and ~/Music folders.
Trashcan is empty (I was in the habit from my old Windows days)
Not using Time Machine. Had not one, but two separate devices fail (My final purchase from Best Buy, by the way. Apple replaced the first one, but when the second also failed Best Buy would not take it back since the serial numbers didn't match).
Deleted apps already. Deleted all photos from the hard drive itself, although some appear to be in my email and my Dropbox.
Will try the disk repair link you suggested. Thanks.
if you have ios devices these backups are part of the "other" category. also includes documents, downloads, anything that isn't in the other headings basically.
i would also recommend checking the size of your user mail folder in the finder window because sometimes it can become full of recovered messages that just keep eating up your HD space. if you see that it's abnormally large and does contain recovered messages you can delete these and empty the trash to free up space as well.
also after removing a lot of items from the mac may be good idea to reindex the HD, the easiest way to do this is using spotlight. the following article tells how to do this:
hope this w/ all the other suggestions helps out!