Photo credit: Kirsty Pargeter

1. Yoomba: Downloadable plug-in lets you chat and make VoIP calls from within your email inbox
2. Campfire: Create unlimited rooms to chat, upload files and share images with your team
3. SharedView: Microsoft's collaboration software enables you to share your screen to up to 15 people
4. Bubbl.us: Web-based application allows you to create, save and share mind maps with other people

1. Yoomba
   
   Yoomba is a downloadable plug-in that you can install inside your Outlook, Hotmail, Gmail, Yahoo and most of webmail services, and that enables you to send and receive VoIP calls and instant messages directly from your inbox. To use Yoomba, no registration is required: just download, install and start using it. Currently in beta it is free to use.
   http://www.yoomba.com/





2. Campfire
   
   Campfire is a browser-based tool that allows you to collaborate online with a group of people. You can create an infinite number of chat-rooms where people can chat, upload files and images, and discuss about them. Storage and simultaneous chatters number depends on the plan you choose. The free version provides 10MB of storage with 4 participants per chat. You can compare the other plans clicking here.
   http://www.campfirenow.com/





3. SharedView
   
   SharedView is an online collaboration software by Microsoft, that you can use to share single application or your entire screen to up to 15 people. To use it, you just need a Windows Live ID account, install the software, and then you can start inviting people to collaborate with them. Free beta.
   get.live.com/...





4. Bubbl.us
   
   Bubbl.us is a web-based application for brainstorming online. After a free registration, you can start creating unlimited mind-maps that you can save in your account, embed in web-pages and blogs and share them with your colleagues, granting them the ability to read or edit the map. It is completely free and you can try it without even registering.
   http://bubbl.us/