So I would say the majority of my time online is spent on message forums. If you don't know what a message forum is, it's basically like an interactive bulletin board. You post a message, and then others can respond to it. Likewise, if others post a message, you can respond to them. I have been a member on various message boards for literally years. I even ran one on my own that was quite successful for a few years before selling my portion of it to the other guy that was running it with me.
As of now, I spend a good amount of time on several different message boards.
Sportbikes.net--I am a very active member of the SBN community. I have over 10,000 posts and have been a member for nearly 8 years now. I have met a few people on there that I communicate with in other ways outside of the forum, primarily playing games with them on Xbox LIVE! I love the site and it's very comprehensive. The Off Topic sections are always alive with content and there's never a dull moment. It's the forum that I spend most of my time online on. Oh yah, it's also the forum that I actively participate in fantasy football leagues on.
TheGSResources--I joined GSR shortly after I got the Suzuki. I'm not nearly as active on that site as I am on SBN, but that's because I primarily use it for finding information about the GS. With the site I've been able to buy a few parts, find places to buy other parts, and find very good how-to articles on various different things that needed (and still need to be) done to the Suzuki. It's a good forum, but not quite as entertaining as SBN.
Paddling.net--I started using Paddling.net when I was looking for the kayaks last year. I utilized it for reviews primarily. It has an EXCELLENT section for reviews on all kinds of products related to canoes and kayaks. This includes reviews of gear, boats themselves, and even different lakes and rivers and such. It's a very basic site, but it's very informative. The forums are also full of very knowledgeable seasoned veterans in the hobby, and they are all very friendly when it comes to answering the many questions that a newbie like me has.
klr650.net--I joined KLR650.net a few years ago, but never actually posted anything there until just the other day. I've used the site to gather information about the KLR, as it is one of my all time favorite bikes. It is also probably the bike that I will buy whenever I end up buying a brand new bike. It's price point is right, it's looks are cool, and it's utilitarian nature is perfect in my opinion for a motorcycle. I browse the forums to find reviews of the bike, to find trip reports and see the gorgeous pictures that people take while out on these do anything bikes.
Geocaching.com--I signed up for Geocaching.com back in like 2001. I remember doing it, but I never posted there until a couple of weeks ago. I remember actually wanting to get into geocaching back before I started working for the Government, but I never got around to it. As I've decided that I want to go and start doing some more things outside this summer, I figured that this would be a good time to start actually using the site. I purchased a cheap GPS unit and started using the site a bit more. It's a great site for this sport, and there is more information there than I think I will ever be able to use. Not only are there informative and great forums, there is also a list of caches that is sorted out geographically that you can browse or search through. The list says many things about each cache, including how difficult the terrain is, how long it should take to do it, and what type of cache it is.
So as you can see, I actively use and participate in a few different forums out there on the web. SBN is still my mainstay, but the others are very useful for more specific things. SBN's broader subject range is appealing to me, and that's probably why I use it more than any of the others.