I've started doing workshops on this recently and have 3 preliminary Powerpoints uploaded that might give you some ideas: There's also an online website and a weekly webinar you can find out about through the Mathfuture site: http://mathfuture.wikispaces.com/
Some ideas for using Web 2.0 tools in Math
1. Blog problems and solutions. Post problems that invite discussion such as : Which would you rather choose a penny a day to be doubled everyday for one month or $1000 a day for 30 days? or "Is 7 really a lucky outcome when you roll 2 dice? Students share their thinking and evidence for these ideasby responding to the post. They can also take turns posting problems for peers to solve.
2. Google Docs is a great place to students to collaborate on creating interesting word problems for peers to solve.
3. Prezi offers an interesting format for students to reflect on their learning in Math. They can upload pictures of their work, discuss what they have learned from different activities and share examples of their "best thinking"
Maybe use comic book creators to explain mathematical concepts. The process of having the student explain it in plain english, combined with the fun you can have with comic book tools, could be a different but engaging way to reinforce some key skills. This was one of the tips I posted in a recent article on Using Comic Books in the Classroom.
We at www.knoodle.com have been struggling with this recently. (Background on us: We make it easy and free/cheap for anyone to upload and synchronize videos and PowerPoint slides, and publish instruction online. We also have the ability to post tests and hold live IM chat.)
While the amount of time an average visitor stays on our website is high, I think we still need to make it more interactive for students. Will game-like quizzes e.g. MightyQuiz or smart.fm keep students more engaged on a computer and still provide educational value? Any thoughts on what has worked for others?
After having completed some math classes in my online degree program I can definitely say that finding ways to teach math through the web is a tough/interesting problem (granted this was Calculus and not 6th grade math, but it is still comparable). For younger students I would try looking for fun little games online (something Sudoku-ish) that represent math concepts.
If you are ONLY looking for online games, then you have to get creative and look beyond anything labeled "math" or "educational" - the really fun games will be tagged "puzzle" or "logic" and you'll have to look explicitly for the connections to your curriculum.
The game teaches logic, sequential thinking, functions, and more. But it's done by telling robots what to do to get through a small puzzle. It doesn't look like "textbook math".
For even more fun, have you ever looked at Scratch? It's a programming/animation language that was designed for upper elementary students. There are many math concepts that can be learned by programming stories and games. The website has TONS of resources about how to use Scratch in the classroom and how to tie it to math concepts.
I attended this webinar today focusing on Interactive Math Activities for K-8 Classrooms. The guest speaker, Collen King, gave very good insights on this topic. I suggest you listen to the full recording of the session by visiting http://live.classroom20.com/archive-and-resources.html.
I think screencasting is a great tool to use within the math classroom. Have you tried having students use programs like Jing to explain their mathematical thinking? I just wrote a blog post about screencasting, with some specific math examples, if you're interested.