picture sets

[Ony]

You can use Photoshop for batch processing them or look up "image sizer", "thumbnail maker", and things like that in Google for a whole list of software that can do it for you.

I have a feeling you're talking about TGP sites where it's a whole page of same-sized images. If that's the case then most good TGP scripts do it all for you. Scripts like Smart Thumbs and Comus Thumbs do this type of thing and even set up the pages for you with tracking, etc.