The National Library of Medicine's MD on Tap (MDoT) application, previously called PubMed on Tap, retrieves MEDLINE citations on PDAs and SmartPhones with wireless Internet connections and the Palm OS. A Pocket PC client is in development.
Read about MDoT's name change & features: PubMed on Tap renamed to MEDLINE Database on Tap (MDoT)
Download MDoT at the NLM website: MEDLINE Database on Tap.