If you are holding a silent auction, we have found the PearlBids package to be a great help.
We've used this innovative software to manage our largest event of the year for three years now, our annual Green Fling for the Marin School of Environmental Leadership. Keeps track of donations, attendees (with contact info), all bids, closing amounts, and prints receipts. You can also link your auction items to eBay, or other sites, and add a picture of the auction item into the interface. You can add and manage as many events as you want. Tech support is excellent too. Sure beats the many years of managing school events in Excel!!