This is a quick recap on the available features of MbUnit 2.15.1:

Fixtures:

Fixture type define how MbUnit is going to explore a class and build the test cases.

• TestFixture, classic unit test fixture,
• TypeFixture, also here, unit test fixture applied to a type (interface mainly)
• CompositeFixture, also here, evolution of the TypeFixture,
• ProcessTestFixture, sequence of tests,
• EnumerationFixture, tests IEnumerable/IEnumerator pairs,
• DataFixture, data-driven fixture

Fixture can be organized in a number of was. Automatically, they are organized by Namespace and Authors, but you can also tag a http://blog.dotnetwiki.org/archive/2004/05/29/277.aspx, and put them into multiple categories. 

Decorators:

Decorators are used on the "method" level to modify the behavior of a given test. Decorators can be chained to combine their effect.

• ExpectedException,
• Ignore,
• Repeat, ThreadedRepeat,
• ConditionalException,
• Duration,
• ExpectedDebugAssertion,

Assertion classes

Aside from the classic Assert class, there are a number of specialized assertion classes:

• StringAssert,
• SecuAssert,
• ReflectionAssert,
• PerfAssert,
• DataAssert,
• XmlAssert,
• ArrayAssert,
• CollectionAssert,
• SerializationAssert,
• WebAssert,
• CompilerAssert