I tried AirSharing and agree with whoever said it was a tad on the slow side.  Right now I just upload my .pdfs to Google Docs and then open them up through Safari.  It's not ideal, but this is the best solution I've found.  I'll pay a reasonable amount for a better solution if I can find one.  I don't think Readdle has a free/lite version, but I think it's received good reviews.