• KoolIM - Web messenger for AIM, ICQ, MSN, Yahoo
  Works behind a firewall or proxy servers. Support AIM, ICQ, MSN, Yahoo, IRC, Jabber, Sametime, RSS News, and Stocks.... We also support Sametime, Simple, SIP, LCS, and Jabber on the enterprise side. We plan on soon launching SMS and ringtone support.
  Web messenger for the web, access instant messaging from anywhere whether you are behind a firewall, at at school, at work and from any other location.
  aim icq instant irc jabber messenger msn sametime skype web yahoo
  in Public bookmarks with aim chat client firewall gtalk icq jabber msn multi proxy yahoo by 9 users
• Twitter At Work and Behind Restricted Networks | Twitxy.com
  Twitxy is a simple solution that lets users behind firewalls and restricted countries get on Twitter. Using funneling technology, Twitxy encrypts your internet traffic and frees you from filtering and democratic restrictions. Simply click Go above and start Twittering.
  in Public bookmarks with countries firewall twitter by 2 users

firewall from all users