Simplemeet.me - offers a text chat place to users without register, grab code, get own chatroom, even it can keep chat log.
Unitag - a web tool that creates QR code easily. You can design colorful QR code for your website.
Zooshia - helps users to create own widget that mixes multiple feeds from across the social web services and add them to your web site.
Fotopedia - a collaborative photo encyclopedia. Anyone can join the community and help build the encyclopedia.