Feedster does a great job of turning an OPML file at a URL into a custom RSS feed.  I found this tip on Frank Arrigo's list of Australian .NET Bloggers (yes, I still monitor the Old Country).  If you have an OPML file visible at a URL it's possible to use Feedster to search them and then consume the results as an RSS feed.  Very cool.

Being able to consume a number of blogs in one feed certainly makes it easier to track a number of blogs in a news aggregator.

Here's the =2004}&sort=date&ie=UTF-8&limit=30&inopml=http://www.sneath.org/tim/ukbloggers.opml&type=rss">RSS feed for UK .NET bloggers and here's the =2004}&sort=date&ie=UTF-8&limit=30&inopml=http://radio.weblogs.com/0124955/gems/aus-dotnet.opml&type=rss">RSS feed for Australian .NET Bloggers.