It's weblog service mania!

A long time ago, Weblogs.com would let webloggers sign up to have their weblogs scanned hourly, and would build a list of which weblogs were updated in the last hour. Suddenly, weblogs numbered in the thousands, making Weblogs.com difficult to use. Thankfully, Weblogs.com made their data available in an XML feed, so other services could use it. So I built BlogTracker (then known cryptically as "the SubHonker Filter"), which used Weblogs.com's list to let users create an account and pick which weblogs they wanted to see. Last year, Weblogs.com implemented a new system, where instead of visiting thousands of weblogs an hour, the weblogs themselves were expected to send a message to Weblogs.com when they updated. Weblogs.com would then visit the weblog to verify that it changed, and update the list.

Before the change to the new system, Weblogs.com also provided a search engine service. Now, DayPop provides that service, using Weblogs.com's list to know when to get the latest web pages.

Meanwhile, LinkWatcher, as old as Weblogs.com, continues to crawl blogs hourly, and still accepts new registrations. LinkWatcher also provides an XML feed of their data. Someday I hope to add LinkWatcher's list to BlogTracker.

Meanwhile, YaySoft performs a similar function to BlogTracker, taking Weblogs.com's list, compiling statistics and letting users make custom lists. Still a work in progress, YaySoft eventually hopes to have a supplemental weblog crawler for weblogs that do not or cannot send the "I've updated" message to Weblogs.com. YaySoft also plans on providing an XML feed from their supplemental crawler.

Meanwhile, blo.gs intends to perform a similar function to both Weblogs.com and BlogTracker, by accepting "I've updated" messages and allowing users to make lists of their favorite weblogs to watch. blo.gs apparently also takes lists from Weblogs.com and LinkWatcher and reconciles them with its own data. blo.gs releases their data in XML, OPML, and RSS feeds, and makes the service's source code available in a CVS repository.

Finally, BlogTrack (not BlogTracker, BlogTrack) lets you specify an arbitrary list of web sites, and instead of visiting the sites hourly and providing a rough list of who was updated recently, BlogTrack visits all the sites when you visit BlogTrack. The result is an up-to-the-minute list of which sites have changed since your last visit. Best of luck to the developer, with this ambitious and resource-hungry project. (The reason Weblogs.com went from visiting thousands of weblogs to requiring the weblogs to send messages is because of the expensive resources required in a continually growing weblog universe.)