Here's an oldie but a goodie. Feed Rinse is a super simple and user-friendly way to tweak RSS feeds before subscribing to them in your favorite reader tool.
With it you can pick which authors or keywords you want to exclude, giving you complete control over what ends up filling your feed reader. For example, on Webware's RSS feed you could very quickly choose to only get posts about Google (which is possible on our main site using tags), or a handful of keywords at the same time.
As Martin over at Ghacks points out, you could accomplish a similar feat on Yahoo's Pipes service, although I found Feed Rinse to be dramatically easier to use. It's a lot like programming a smart playlist in iTunes, with simple drop-down menus, instead of Pipes' system which requires you to create programming strings.
One thing worth mentioning is that Feed Rinse is smart enough to know you're going to take your newly created RSS feed elsewhere, and as such has special links that will send your feed out to various reader services like iGoogle, My Yahoo, Netvibes, and others. There's also a bookmarklet that lets you tweak the RSS feed on any site you're on with one click. Both are nice touches that save you time.
Feed Rinse is completely free to use, although you're limited to creating and managing just 500 filters per user account. The service previously had a premium and plus plans, however these disappeared two years ago in place of a unified offering.