Sometimes you need to try some code quick, do a little reaserch over a framework, etc. You can either:

- create a cs in your main proyect, write the code, test it and delete it. 
  The bad thing is that you'll have to delete it (or leave crap), it could cost more if your solution 
  is too big (and you haven't properly addressed compile time issues).
  
   In resume, can be slow and you loose the code

- create a new Vs proyect, and write the code there
  The bad thing is that you'll probably have a bug number of UnitTestProyect11 and if you want to look at the code
  again, you'll never find it

And finally you can have a solution like this one.
I have have here a lot of code samples that I'll find useful with the advantage that I can find them later, 
improve them, blog about them, share it with my collage to improve and even teach them using this samples.

This is for me but I thing anyout can find it useful.