26. Evernote

Evernote isn't exactly a "social" application. It is, however, very Web 2.0 in its insistence on making data entry painless wherever you happen be - on your phone, on the web or on your desktop. You can use Evernote to clip parts of web pages (or the whole thing), enter free-form notes yourself or save images and other media in a single spot. Evernote comes with a desktop client, a Firefox browser button and an email address that you can email to (or text to an an email address) notes/media/thoughts as well. For those of you who got into the Jott application when it was featured earlier, you can take that Evernote email address, add it as a Jott contact and "Jott" your notes via your phone to Evernote. It is free and offers 40 MegaBytes of uploaded data per month - that's a lot of random thoughts you can capture pretty easily!! Their own description of their services comes from their Help section:

Evernote is a Web Service that helps users manage all the digital information most relevant to them. The Service can be accessed through free, user-friendly Evernote software running on a personal computer or mobile device, or any Web browser.

This isn't the only note-taking software that is available, but it is the best example of a note-capture system that uses Web 2.0 theory (be where your users are!) that I've seen. No matter where I am, I have no problems dropping information into my Evernote account. While it isn't precisely social, it does allow you to share portions of your data - any of your notebooks can be easily shared with the public. It also takes advantage of tagging to help you organize your thoughts and your notebooks in a way that makes sense to you!
Evernote is free, but it is still in beta and requires an invite. I have 19 of 'em left and I think Bobbi might have a few as well. Just leave a request in the comments or email me and I'll hook you up!

24. Greasemonkey

Greasemonkey is a browser add-on (extension) for the Firefox browser (no equivalent in Internet Explorer, sorry) that allows little snippets of JavaScript code to manipulate the web pages visited by the browser. After you install the extension, you can then use it to install and manage scripts that do everything from change ads on pages from the original ad graphic to random Flickr pics to adding information from one site (say, your local public library's) to another site (say, Amazon.com). This is all done via the JavaScripting language. You aren't a JavaScript expert? No problem, people have been writing scripts - and sharing them - for years. Just about any site that gets more than a couple of visitors a day will have some scripts that can adjust its user interface, functionality or both. You can find an exhaustive list of scripts, arranged by website, on the Greasemonkey User Scripts wiki or you can find a number of "best of" lists that link to the most popular, useful or fun scripts that author can find, some specific to particular sites like del.icio.us or Gmail.
I use Greasemonkey to add a "twit this" link to my Google Reader web page - giving me a quick way to share what I'm reading with my Twitter buddies. I also use the Better Gmail script to improve the way the already very cool Gmail service works for me! Spend some time browsing around the various script sites, seeing what is available and what might improve your browsing experience (pay attention to all the social sites that have scripts - FriendFeed, Twitter, del.icio.us, blogger, Facebook, etc. - some of them are handy in helping with information overload).