Some interesting things here.. the category jump is nice at photobucket,
but I would suggest to take into consideration some techniques used on another gallery site: deviantART: where ART meets application!
The advantage they have, is that they are (in the newest version) very concious about saving ressources.
Example: images and categories on home page are strict minimum
Only that instead of generating a semi-transparent overlay it overlays a real page. whitout using ressources, taking the previous / next links from the images on mainpage etc...
They also have a similar category jump. showing only top level cats on mainpage and subcats only where you are: this also saves a huge amount on ressources.
thats my 2 cents