RSS feeds provide an interesting challenge when it comes to filtering results. I recently posted on Omea, a desktop aggregator that will notify you of incoming matches. Another way I manage this issue is to merge a bunch of related RSS feeds, usually using Yahoo! Pipes, and then applying filters on them before they even reach my RSS reader. A recent entry in this area is Jumbra.
One reason that sites like Jumbra are interesting is because they are easy to use. Pipes can be daunting, as powerful as it is. I have directed users to Feedrinse as a simpler way of doing this sort of aggregation and filtering.
Jumbra’s advantage is that you can group up to 30 feeds (pasted in, line by line) into a single aggregate feed. Once you have that unified feed, you can then repurpose it in a variety of ways. I like to send them through a word filter – and Pipes might still be the best option for this if your reader doesn’t support keyword filtering – but you could also take a couple of newsfeeds from your law firm and aggregate them into a single one for an intranet or client-facing site.