If you can solder then Crossroads boards are a good idea.
If you want a small Arduino but don't want to solder then your best options are:
The Nano - http://www.gravitech.us/arna30wiatp.html
- basically the same thing as your Duemilanove but in a smaller form factor. I've been using the Nano as my go-to breadboard Arduino for several years now. No problems.
The Teensy - http://www.pjrc.com/teensy/index.html
- 3 boards that are software compatible with the Arduino but use different CPUs. I got the Teensy 3.0 about a month ago and like it a lot.
The Pro Micro - https://www.sparkfun.com/products/11098
- Similar to the Teensy 2.0. Never used it, but in general SparkFun knows what they're doing.
There are actually several others too - http://arduino.cc/en/main/boards