I'm a lazy developer.  If I can save keystrokes I usually try to.  For instance, I put my css files in the 'c' folder.  Javascripts go into the 's' folder along with any other scripts I have.  I usually also like to use single charecters for querystring variables.

When naming my business and data layers, I got into the habit of using the namespace Biz and Data.  Lets me type in similar keystrokes over a variety of projects.  Problem comes when two or more of these projects have to work together.  All of a sudden things get confusing fast.  The compilier will also complain if you have a similarly named class in another assembly.

What to do?  Pretty easy, add a parent namespace that is short enough, but allows you to specifically target a particular Biz or Data layer.  Right now I've been using acronymns and it seems to be working well.  Now instead of Biz I have MNP.Biz or LS.Biz.  Two to three extra char's ain't going to hurt.