Wirelessly posted (HTC Diamond: Mozilla/4.0 (compatible; MSIE 6.0; Windows CE; IEMobile 7.11) Sprint MP6950SP)
Wow! You're really filled up!
You know, I have noticed that sometimes even when you specify to install to internal storage when installing a cab that some apps will still install all or some data into device memory.
I have been correcting this by moving folders to internal storage with sktools. You could do the same using sktools or memmaid like rhacy suggested.
The rom you are running could be eating up most of your device storage so you could just try a different one or yes you could definitely try cooking your own. OMJ's Kitchen is highly recommended. I'm sure you could probably find a lighter rom that you could add to that won't eat up all your device memory. Most chefs will clearly state how much device memory is used by their rom. I wish you the best!!