I need to find out some IM service which will be part of our inner office system. I want it to be available in the form of Firefox/Flock/Thunderbird extension and offers instant messaging and file sharing…so last few days I systematically tested all available IM extensions which I found (If I missed some another such extension please let me know).
Here are extensions which I’ve tested with short list of main features (and the missing features). In the list are also two servicies which didn’t meet requirements above but I put them here because I like them – Google Talk and Pownce…

AllPeers (http://www.allpeers.com/)

  • instant messaging
  • really good files sharing
  • bittorrents (it simple and nice)
  • doesn’t support other IM services

Google Talks (http://www.google.com/talk/)

  • instant messaging
  • no files sharing
  • one account (IM, email, calendar)

Me.Dium (http://me.dium.com/)

  • instant messaging
  • no files sharing
  • UI is not so pretty and usable as on the first look

Pownce (http://www.pownce.com/)

Pownce is another sharing service but still in not for public use (invitation key is required for sign up). Client of this service is using Adobe AIR technology and looks cool – this is the only reason why is here ;) … (here you can see some screenshots: screen 1, screen2, screen 3)

xmpp4moz (http://dev.hyperstruct.net/xmpp4moz)
This isn’t a service but this is extension which brings support of XMPP protocol to Mozilla-based applications so it can be used for building your own chat application.

SamePlace (http://sameplace.cc/)

  • instant messaging – using XMPP protocol so you can use your Jabber or Google Talk account
  • no files sharing
  • still little buggy



Conclusion
I’m choosing AllPeers because they have everything whats needed for communication and sharing in small groups and if in future will be added support for Jabber or Google Talk will be unbeatable. What I’m missing the most is support for Thunderbird and I’m thinking about implementing it by self.