Icon: src/qt/res/icons/clock*.png
Designer: Wladimir van der Laan
License: Creative Commons Attribution

Icon: src/qt/res/icons/send.png
Icon Pack: Vista Style Arrow
Designer: Icons Land
License: Freeware Non-commercial
http://findicons.com/icon/231371/right3green

Icon: src/qt/res/icons/address-book.png
Icon Pack: Farm-Fresh Web
Designer: FatCow Web Hosting
License: Creative Commons Attribution (by)
http://findicons.com/icon/163938/book_open

Icon: src/qt/res/icons/connect*.png
Icon Pack: Human-O2
Designer: schollidesign
License: GNU/GPL
http://findicons.com/icon/93743/blocks_gnome_netstatus_0

Icon: src/qt/res/icons/transaction*.png
Designer: md2k7
https://forum.bitcoin.org/index.php?topic=15276.0