There are so many to choose from !
You have 3 variables to consider - build difficulty, performance and cost.

A kit will be easier to build than a rig from schematics. If you are reasonably confident at brewing your own then go for the 2n2-40. Designed by Jim Kortge K8IQY (www.qsl.net/k8iqy) and supported by an active group (http://groups.yahoo.com/2n2-40), it is quite easy to build and is a super performer. Getting the parts is the hardest bit.

Kits are easier. If you already have a home station and are looking for a 'fun' project then the FOXX (used to be available from Kanga but currently O/S) would fit the bill, along with a few other 'build in 2 hours for $30' type kits. Just don't expect fantastic performance, it's amazing what can be done with a cheap rig in an Altoids tin, but I wouldn't want one as my only rig.

The MFJ QRP-Cub series of kits perform quite well, are cheapish and easy to build. The 40 or 20m versions will get you loads of contacts.

Then there's the Elecraft K1 (www.elecraft.com). More expensive, but very good value for money. A little bit more of a challenge, yet still beginner level. This could be used quite happily as your only rig.

Hope this helps !
73 Steve, G4GXL

Link:  http://www.g4gxl.com