Gateways
Netvibes | Me: A double-sided portal that allows for public and private views, as well as friending associates.
Flickr / PicLens
iGoogle: A personal page with no external web presence. Content can be organized into tabs, Google App integration is a plus.
Mahalo: A human edited search engine, with the goal of having 10,000 handcrafted result pages for the most popular topics. Firefox toolbar allows users to create user and topic pages.
Microcontent
Twitter | Me: Still the most popular microblogging platform around, twitter has battled uptime and performance issues almost since it's creation.
Tweetcloud | Me
Tweetstats | Me
Jaiku | Me: Purchased by Google, it's the lead competitor to Twitter. It allows replies to posts, which gives rise to threaded discussions within the site.
Pownce | Me: Microblogging combined with file-sharing.
Digsby: Desktop client for tracking instant messages, email and social network updates.
Social Networking
Facebook
Games: Slayers vs. Zombies vs. Pirates
Outside Apps: Del.icio.us, GoodReads
GoodReads | Me: Similar to LibraryThing, GoodReads networks like-minded bibliophiles. Readers can place their books on a variety of shelves, write reviews of those books, and create discussion groups.
SocialThing: A social networking aggregator that combines posts from services such as Facebook and Twitter into a single timeline
Shyftr: RSS reader that allows users to share and comment on each other's feed items.
Productivity
Google Docs Create documents online, edit them in real time with other people, create forms that feed Google-powered spreadsheets, and use data in spreadsheets to display graphs on a web page.
Evernote: Sychronizable note-taking system for Mac, Windows and mobile devices.
Twiddla: A team whiteboarding application, allows people to chat and talk in real time, draw on the canvas, and co-browse web pages.
Voicethread | Example: Creates group conversations around images, docs and videos.
GrandCentral: Voicemail tools.