Niche Research Bonanza-Free Trade Publication Site
If you're interested in researching tens of thousands of niche possibilities, you could do worse than TradePub.com, which gives you free access to a cornucopia of vertical magazines in almost every conceivable field. From Pig International to Pharmaceutical Executive to the perhaps more familiar Target Marketing, this is where you get serious about researching an industry. Only downside is that you have to fill out the dreary computer equivalent of those subscription questionnaires you will remember from the trades in your own (former?) line of business--for each subscription you request.