Photo credit: Byron Moore

1. ScribbleWiki: Online collaboration service allows you to create wikis for you and your team
2. Yuuguu: Free downloadable software lets you share your desktop and remote control PCs
3. Retroshare: Open-source P2P software enables you to chat and share files with your friends
4. IMhaha Access all of your IM accounts from one place, right from your browser

1. ScribbleWiki
   
   ScribbleWiki is an online collaboration service that you can use to create personal and business wikis for free. You can create an unlimited number of wikis, with unlimited pages and users. Afetr you create a wiki, you can send people the URL, or invite them and grant them the ability to edit and change your wiki pages. Free to use.
   http://scribblewiki.com/





2. Yuuguu
   
   Yuuguu is a free downloadable application that allows you to share your screen with anyone. After you download the small client software, available both for Windows and Mac, you can start sharing your desktop with one, and let them control it for you or vice versa. You can also chat with the meeting participants. Free to use.
   http://www.yuuguu.com/





3. Retroshare
   
   Retroshare is an open-source P2P software that enables you to collaborate and share files with your friends. After a small download (4MB), and a simple registration, you can start adding your friends to your private contact list: you can chat with them, one-to-one or in groups, share any file you want, and also browse all the files they're sharing. Free.
   http://retroshare.sourceforge.net/





4. IMhaha
   
   IMhaha is a web-based multi protocol instant messenger that lets you connect to all of your IM accounts, from one place, right in your browser. Right now it supports MSN, Yahoo, ICQ and AIM, and it allows you to access more than one account at once. You can also register to IMhaha itself, to make it remember all your credentials for you. Free to use.
   http://www.imhaha.com/