Display random images from media gallery

Hi guys,
I’ve been trying to solve this thing for a while and I still didn’t find any working solution.

Here’s what I want to do:
I want to display random images from WordPress’s media library in sidebar. The best solution would be loading 5 (fullsize) images from the gallery (if it’s possible I’d like to specify a post/page with attached images I want to randomly display) together with their descriptions. Nothing more, nothing less. I’d process those images by timthumb.php to adjust their size.

Is there any way how to do this? I don’t mind PHP solution or widget solution. All I need is fully customizable output…

Thanks a lot, Machi