Arduino Netduino: Oscilloscope and Logic Analyzer

I have been thinking about buying a nice Oscilloscope/Logic Analyzer ever since I bought that little cheapie one I bought a few weeks ago.  But then I thought that it would be cool to build one.  I know how they work, and usually my needs are pretty low tech and low bandwidth.  As a result I am going to try to build one using either an Arduino or Netduino.

Here are some of the plans I am reviewing, mainly since it will definitely be more expensive to build then to buy, but it would be cool to have the experience:

http://www.practicalarduino.com/projects/scope-logic-analyzer , this one looks good!

http://www.instructables.com/id/Girino-Fast-Arduino-Oscilloscope/, fast, but complicated, if you have built out other kits or projects, this is for you.

http://mitchtech.net/arduino-oscilloscope/ cheap, requires only an UNO board and a wire

http://sebastiannilsson.com/en/k/projekt/realtime-plotter/, cheap, not a true Oscilloscope, but close enough and simple.

I am definitely going to give one of the harder ones a try, but the last two are likely good enough to solve most problems that require an O-scope (Oscilloscope).