There's a Flickr
Hi-Res Science Fiction Book Covers pool that's incredibly useful for Sci-Fi/Fantasy. Also a
couple of
other book cover albums I've found as well. (Mostly Sci-Fi/Fantasy as well.) And
Fantastic Fiction is a good resource, but I can usually find higher resolution scans elsewhere than what they have.
It is frustrating when you just can't find any decent resolution cover for a book. And it amazes me how many
purchased eBooks will have no real cover image in them. The Amazon page will show a cover, but it's not actually in the eBook itself.
I'm more inclined to overlook this if the book was a freebie, but if I've paid for it, it should have a bloody cover image in it!
