Btcd
This page is a stub. Help by expanding it. btcd is a full-node implementation in Google Go by Conformal. Its project page on GitHub says:
"It currently properly downloads, validates, and serves the block chain using the exact rules (including bugs) for block acceptance as the reference implementation (bitcoind). [...] btcd does NOT include wallet functionality and this was a very intentional design decision."
See also the btcd tag on Conformal's blog, especially the "ready for public testing" announcement.