RSS feeds are a fantastic way to quickly see the latest news from your favourite sites, without having to check those sites frequently. Safari supports RSS natively, and Firefox and some other browsers support news reader extensions, but I prefer to use a web-based aggregator called News Gator Online, set to my homepage. It's free, and does a great job of displaying content. As you would expect, it updates itself, so if you leave a tab open in the browser of your choice, you can see all the updates without refreshing.
The same company that created NewsGatorOnline has a wonderful RSS application (i.e. not browser-based) called NetNewsWire, which does a wonderful job of organizing multiple feeds. This is not freeware, but you download the demo here. It features a very intuitive interface and I'm really digging it so far (update: there is a new freeware version called NetNewsWire Lite 2.1).
While I'm on the subject of RSS feeds... here's a tip: some sites like Craigslist create RSS feeds based on a custom search. This means you can perform a search once, and your RSS aggregator will keep a constant eye on the site for new results. For example, I searched for "foosball" on Vancouver's craiglist (for sale category), and it created this RSS feed for me. Now NewsGator will let me know whenever someone in Vancouver has a foosball table for sale.