Or do a search
(Not trying to be mean, but it has been discussed in great detail many times.)
BeamReader, DocHawk, PDF To Go, Repligo are the main choices for PDF readers.
Repligo was nicer but it's like 30 bucks... the PDF To Go is part of Docs To Go Premium so it will cost you 70 bucks for DTG Premium... Never used Doc Hawk but it does cost a good penny.
I used the BeamReader beta, I haven't used it since it's out of beta.. doesn't cost something nowadays?