Internet needs censorship and a secret police... That's what it really needs! Anyways, sorry about my offtopic. There is this site: www.freetopkeywords.com, I am not sure how accurate it is or how often is it updated but - it will give you a general idea about what pays most. Afterwards you can go to your Adwords Tool and search for up to date info and keyword variations. Why would you waste your time with something that doesn't pay? eh?
Make something that will be interesting and USEFUL for people. The majority of sites are rubbish and drivel. You have to choose the theme you're interested in and develop in...
Do whatever you are passionate about. You find the most successful entrpreneurs are those who love what they do. The Internet is like a universe of information, whatever your passion there will be someone else who has the same passion. Explore and enjoy! Let us know what you decide to do, this forum is a brilliant start, everyone seems to be really caring and friendly. I am new here and already feel really welcome!