Blog moved to www.jeffreypalermo.com
There are plenty of ways to run your NUnit tests while developing and during the build. JetBrains has released a unit test running add-in for Visual Studio, and they are giving it away for free. It's called UnitRun. The screenshot to the right shows how you can execute a test from the margin. I like to map CTRL+T as my shortcut to run a test.

You can also run all of the tests in your solution with a larger window. (above) This isn't a new release. It's been out for some time, but I'd never mentioned it. I use unit run. It's actually a feature of the larger Resharper package.
Other notable unit test runners are:
About Jeffrey Palermo
Jeffrey Palermo is a software management consultant and the CTO of Headspring Systems in Austin, TX. Jeffrey specializes in Agile coaching and helps companies double the productivity of software teams. Jeffrey is an MCSD.Net , Microsoft MVP, Certified Scrummaster, Austin .Net User Group leader, AgileAustin board member, INETA speaker, INETA Membership Mentor, Christian, husband, father, motorcyclist, Eagle Scout, U.S. Army Veteran, and Texas A&M University graduate.