Bibliotik and other good ebook site recommendations

Hi,

Can anyone recommend good ebook only torrent sites?
I've seen Bibliotik mentioned a lot but it doesn't appear to be open to new users :(
i've checked some others which are ok but would love to find sites with a nice/intuitive design, categories and selections of (preferably) mobi. files,
I use Pirate Bay for general media but its not really geared toward browsing individual ebook releases and doesn't offer categories for different genres/types,

any help greatly appreciated,

Cheers