Here are some site/places where can pretty much find out what's hot. Some good Niche Research..
They're not linked, but easy enough to get to from Google's search page. The one's with ***, are the one's that I like the best. Which doesn't means the others are not valuable.
Google Tools
Google Trends
Google Insights for Search *** - much more effective the 'trends'
Google Blog Search
Google AdWords Keyword Tool
Clickbank
Cbtrends
ClickBank Search Engine
ClickBank TopSites
Clickbank Marketplace *** - This is where you do your Clickbank research.
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