Until today I'd only heard of OpenSSL and GnuTLS.

Wikipedia lists: Botan, cryptlib, CyaSSL, GnuTLS, MatrixSSL, Network Security Services, OpenSSL, PolarSSL, Schannel, Secure Transport and JSSE.

I'm curious to see how much "market share" OpenSSL has given the recent bug, and what kind of operations specifically DO NOT use OpenSSL, in favour of another implementation.