I'm wacky about wikis. If you've ever browsed through Wikipedia, you know what a wiki is. Basically, it's a web page (or group of pages) that anybody can edit from any computer anywhere on the planet. (Which is why you have to be careful about doing serious research on Wikipedia.) But did you know that you can harness the power of wikis to develop your own personal projects? Whether you want to plan the family Thanksgiving dinner menu with your sister, or organize your writing research, a wiki might work for you.
Wikis work equally well for group projects, or for solo endeavors. Many wiki sites offer free wikis for a certain number of users, usually between 3 and 5. If you have a large number of people you need to collaborate with, you'll probably have to pay a monthly fee. Check out the article entitled Four Free Wikis Worth Trying by C. G. Lynch to get an idea of what's out there.
I have a bunch of wikis through PB Works (formerly PB Wikis), including one that I use to organize my on-line writing research. Whether I'm working on my laptop or my PC, I instantly have access to all of my research notes, including direct links out to my original sources. Since I set my wikis up as private wikis, nobody has access to them but me. If I want to invite somebody in to collaborate, I can choose what level of access I want that person to have. I can give them read only access, or I can give them full editor access. The power is intoxicating!
There's a very small learning curve involved in setting up and using a wiki, but it's worth the minimal investment in time you'll make up front. Google "wiki videos" for videos extolling the joy of wikis. Here's one to get you started.