Being a K3 owner I've found the mobi/prc uploads area to be my favorite. I bought a K3 mostly for PD books and was disappointed that the ones from Amazon and Gutenberg were so poorly formatted.
I like it because many wonderful people format and upload those books. In particular crutledge, who has literally uploaded 1000s of books, all very well done, and the sorely missed Patricia
https://www.mobileread.com/forums/forumdisplay.php?f=128
As to how it could be improved, I dunno. Maybe a "Thank you" button or something to let you know you appreciate their efforts, since you can't always give them karma.