A few predictions for what we'll see online in 2008:
Facebook hits its limit. I predict some more ad snafus a la Beacon, and the 3rd party apps become overwhelming and all-too-reminiscent of MySpace. NB: The AdBlock Plus Extension and AdBlock Element Hider can block most FaceBook ads, and there's a GreaseMonkey script to reset MySpace pages to the default template.
Twitter is on the rise. Microblogging in general will increase, and someone will add in more community and meta-organizational features to it. There's a lot of 3rd party activity around Twitter to add in location awareness, tagging, and so on, so maybe Twitter, Inc. will take the hint. Also, with improved community/groups tools, lots of people figure out that Twitter's a fast way to have a mobile communications strategy, which will be much more important as iPhones and other web-capable phones are useful and popular enough to expand past the blackberry crowd.
Single Sign On gets closer OpenID has been quietly gaining steam, and will continue to do so. If Google and Yahoo decide to place nice, there's a big win. Microsoft will get pissy about this, but it might already be too late. Integration in general will become key. Evidentially, other people are thinking the same thing.
Social Bookmarking grows up Del.icio.us style and digg/stumbleupon style bookmarking sharing sites morph and follow my Twitter predictions; adding more social/community and organizational tools. They may even get mashed together.
GeoLocation is the new tag cloud 2007 saw everyone adding geolocation to their sites (Flickr Mappr, Google Maps API interfaces turning up everywhere, multiple FaceBook "where I've been" vanity maps, Twitter location tools...) with increasingly easy integration tools, adding mapping to anything remotely geographic will be in 2008 what adding tables and animated "email me" and construction-man graphics to your index.html was in 1998.
A new peer production site will show up Wikipedia and its ilk will continue going strong, but there's an increasing convergence of easy to use tools that enable users to collaboratively build information stores. It just takes one to hit a market ripe for user-generated content to really do well. My prediction? Education, spurred on by a need to support the implementation and follow-through lacking OLPC project and a global workforce that's been trapped doing creating and turning in make-work homework can now easily mobilize to add to global knowledge store.
Microsoft does dumb things in a quest to drive more people to buy Vista. This could include locking out non-Vista users to certain ActiveX driven webpages and/or their MS Office Online. Most of these will backfire and hopefully push more people to Apple and Linux. OK, so that one's almost a given. Update Microsoft's Office Service Pack 3 disables legacy file formats. Way to start the year, Bill.
Google buys Yahoo OK, that's a long shot, but it'd be awfully interesting, since Yahoo woke up to web 2.0 and made some strategic purchases (Flickr, del.icio.us...) and has done some great work with the Flock browser. I can only imagine Google getting a little territorial here. We're all in deep trouble if Google ever turns evil.