I like the aluminum patches you can buy inexpensively at Home Depot, Loews, etc.
The newer ones are sticky backed. Just stick over the hole overlapping by a few inches and apply joint compound. Sand and apply more joint compound to smooth the edges into the wall. These are good for smaller holes such as grapefruit sized.
http://www.homedepot.com/webapp/wcs/...egoryID=502707