Here are some tips that can be very helpful to market research:

Clickbank - high gravity products are a good indication that the niche is hot.

Amazon Best Sellers - you can find all the popular products in any category.

Ebay Pulse - similar to amazon best sellers. very useful for drop shippers.

Flippa Sold Sites - good indication on what is hot at the moment, useful if you are looking to flip your site in the near future

Google Trends - great indicator for current trends.

There are many more, but this are the ones I primary use for my micro niche affiliate sites.

Thanks! I rely on traffic patterns myself: Quantcast, Compete, Alexa not so much anymore

One more tip from me is that "Don't Sell Just Tell"
This is one of the best techniques to keep with you while indulge in marketing.

I haven't beem very good at Clickbank. If someone has a good book on it, I would appreciate if you share. I want to do good on CB.

Thanks

Thanks for great tips on market research it was helpful to me too.

Thanks Again!