As Jeff mentioned in his post:
There is a default tag filter on http://stackexchange.com/ but you must be logged in:
click "Tagged questions" at the top
click "my filters"
Then look for the default "Favorite Tags" filter.
You can browse it in your browser, or have it emailed to you, or get the RSS feed at the bottom of the page (also present in the headers, too, if your browser auto-detects).
