Useful regular expression tutorial
Is there a good tutorial on using regular expressions, especially with grep? I tried googling for some, but most tutorials are too basic and cover things I already know.
Regular-expressions.info has a tutorial section. This site is pretty comprehensive for regular expressions in general, although the emphasis is on support in scripting and programming languages.
The J. Friedl book, (mentioned previously), is definitely an outstanding resource, and essential reading if you are serious about doing what the title says. If you're just in it for a I'm-in-a-hurry quick-online-scan, then you might want to try the link above, or just hit up a search engine and browse around.