what's the best host-able type of file i could save a document i've worked on in photoshop as, and what website can host it? as far as i know, out of the list of possible files, image shack only allows .gifs...is that the best i'll get? ~

You can host .Psd files up to 30 megabytes without registering on imgdevil.com and 60 with registering.
I personally set it to private when I upload so randoms can't steal my work =]
If you don't it gets shown in gallery

(It will also do lots of other file types)