TrouSerS - An open-source TCG Software Stack implementation.
Very useful and necessary. Would have rated a "just OK" on design due to verrrrrrrry few comments in the code. But then maybe the design is just in the TCG documents. Support is good in trousers users list
TrouSerS is a very nice implementation of the TSS stack as specified in the TCG TSS 1.2 specification. It is much easier to use than I expected.