My kids are working to waste large swathes of my time by introducing me to addictive games
2048, via my daughter
QuizUp, via my son
Those are the quickies. For more serious gaming on the iPad, I have been playing a bunch of euro-style board game ports, including Lords of Waterdeep, Agricola, Eclipse, Dominant Species, Small World, Ticket to Ride. All recommended. I have heard rumors of iOS apps for Dominion and 7 Wonders, two of my current favorite board games, but I have seen anything appear. Board Game Geek has an iOS blog (beware, the format is uglier than a geocities page). I downloaded Pandemic but have not played it. There are also ports of Carcasonne and Settlers of Catan but neither of those are my favorites.
I have also enjoyed the port of Baldur's Gate II to the iPad. This is still, perhaps with Neverwinter Nights 2, the best AD&D rules RPG for the computer. The only problem with Baldurs Gate is the graphics on the PC are dated, but they work fine on the iPad. I downloaded a Master of Orion port the other day but have not tried it yet.
But for REAL time wasting, I look forward to this fall when there is apparently a new version of Civilization / Alpha Centauri coming out. Trying to have my desk cleared before then.