A site that has a compendium of links to genealogical resources all over the US, Linkpendium is worth a browse.  Not all the links will take you to sites that provide free digital information, however, if you find a clue or tidbit that you’ve been searching for, it may be well worth the investment.

One thing I like to do at pay sites is sign up for a trial membership and spend that “free” time diligently searching their records to see if they have something of interest.  If not, cancel before your trial period ends and nothing lost.