One of the easiest ways to get traffic and make money is to give people what they are looking for. How do you find out what people are looking for? Well, here are some resources in no particular order:

http://buzz.yahoo.com/overall/ - top 20 searches at yahoo.com

http://50.lycos.com/ - top 50 searches at lycos.com

http://hotsearches.aol.com/

http://www.foia.cia.gov/Top25PhrasesMonthly.asp

http://sp.ask.com/en/docs/iq/iq.shtml

http://technorati.com/pop/

http://www.google.com/trends/hottrends

http://www.dogpile.com/info.dogpl/searchspy/

http://inventory.overture.com/d/searchinventory/suggestion/

https://adwords.google.com/select/KeywordToolExternal

http://pulse.ebay.com/

http://buy.ebay.com/

There are plenty more - I found most of these by googling “top searches”