1. Twitter: While I much prefer the functionality of the open source Identica, Twitter remains a vital point of contact for me with those in the science and education communities. Given Twitter's 140 character limit, I often make use of a tool such as LinkBunch to enable sharing of a number of related links in one short URL. [Online, free]
2. Google Reader: I recently made the shift from NetNewsWire to Google Reader as my RSS feed reader of choice and am very impressed with its stability and options for connectivity with other Google applications and users. Active script communities help contribute further functionality to Google Reader's web interface. [Online, free]
3. Socialite (née EventBox): There is so much to be learned from our social networks and RSS feeds that I need an effective tool to filter and categorize all of this information while also enabling me to contribute easily to it. I use Socialite for this purpose, combined with OmniGrowl for on-screen notifications of replies and new posts featuring keywords of interest. [Socialite: Mac, commercial; OmniGrowl: Mac, commercial]
4. Keynote: For presentations that look great and are a joy to design. Al Gore uses it. [Mac, commercial]
5. Tags: While I still maintain a folder structure on my laptop, Tags enables me to add an additional layer of information to files, folders, and, wonderfully, email messages. I think of it as an off-line Delicious (see below) for all the data on my hard drive. [Mac, commercial]
6. Weebly: The free website builder that I use to create and maintain this site. Easy to use, stable, downloadable archives, and excellent support and development. The Weebly team has just announced support for educators and classrooms. [Online, free/commercial]
7. Delicious: The venerable online bookmark sharing service. Browsing the network is a wonderful experience of serendipitous learning and can become quite addictive. [Online, free]
8. Adium: An instant messaging client that supports a multitude of services, including Twitter and Facebook chat. Stable and infinitely customizable, with an active developer community. [Mac, free]
9. iGTD (discontinued but still available for download): Essential for keeping track of all my projects and related activities, iGTD applies David Allen's (not Daevid Allen's) Getting Things Done approach to task management and connects with my PDA and calendar and email software. Bartek Bargiel, the software's creator, has since moved on to work on Things, a similar GTD application. [iGTD: Mac, donation; Things: Mac, commercial]
10. iTunes: My tool of choice for subscribing to podcasts and for maintaining daily sanity. [Mac/Windows, free]