There was a thread about how to offline/delete clips and the media they reference some time ago, but I can't for the life of me locate it to post in, so I'll start anew...
I just discovered this today, and I'm about 99.9% positive it was not in PPro CS3 prior to the 3.2.0 update, but there appears to now be a way to delete master clips in a bin and the media files they point to in one step. Previously, if I wanted to trash media, I used the Make Offline function and selected "Media Files are Deleted", and then deleted the master clips themselves. Not a huge problem, but a seemingly needless two-step process (plus the confirmation dialogs).
Today, I mistakenly pressed Ctrl+Delete while I had some clips selected in my the project panel, and to my happy surprise, I was greeted with a dialog I'd never seen before. It's a simple box called "Delete" with a checkbox named "Delete media file(s) from disk". If you hit OK, the media files themselves are deleted (permanently, mind you--no layover in the Recycle Bin) and the references are removed from the bin. Cool! This is something I've been wanting since I began working with PPro.
Looking in the keyboard customization, under Panels > Project Panel, there is an option called "Delete Selection with Options". I really don't remember seeing this before--I've gone over all those options with a fine-tooth comb. Anyone know if this was added recently, or if it's always been there? It's not a big deal either way, but it was a happy find for me--and I seem to remember from the thread I referenced earlier that some were looking for this option.