I haven't tried MBUnit for doing .NET Unit Tests, but it looks to be a decent alternative to NUnit and in many ways may have a shorter time between new release dates.
Here are some of the features of MBUnit:
Fully compatible with NUnit, csUnit fixtures. No change to the code needed, besides changing imports,
GUI, Console Runner, NAnt task, and Visual Studio Add-in with NUnitAddIn available,
New Test Fixtures:
- TypeFixture: fixture that applies to instances of a particular type (very nice for testing interfaces).
- EnumerationFixture: tests IEnumerable/IEnumerator implementations
- OrderedCollectionFixture: ordering tests on collection
- ProcessFixture: execute a sequence of tests
- ...
New Test Decorators: repeated tests, "timed" tests, load tests, multi-threaded tests, etc..
Extensible fixture definition scheme: MbUnit was designed with evolution and new fixture integration in mind.
Support for .NET 1.0 and 1.1
Supported by DotNetMock
You can read and download MBUnit from here.