Pynode
https://bitcointalk.org/index.php?topic=94645.0firef

Coin Control
https://bitcointalk.org/index.php?topic=144331.0

BIP32 (HD Wallets) implementation in Ruby
https://github.com/wink/money-tree

Coin Covenants
https://bitcointalk.org/index.php?topic=278122.0

libbitcoin
https://github.com/spesmilo/libbitcoin

BIP0039
https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki

Bluetooth Bitcoin transactions
QT .8.5
SHA Collision rewards
and more…