Lonely Planet's website is quite good for letting you know if you need a visa for a certain country or not.
http://www.lonelyplanet.com/
But it's always best to check with the countries own website as some countries you will require a visa before you arrive there or sometimes you can get them on arrival.
Also if you have an older passpord you may require a visa before you arrive in the country if you passport is not machine readable.
Remember that Visa requirements can change quite quickly.
I agree! LP has tons of
I agree! LP has tons of vital information that most travelers (new or not) never really think about before they start to plan a trip. I have no idea how many times a passenger of mine was at the airport and denied boarding for not having the proper paperwork, even after I told them numerous times. Countries have these requirements for a reason. :) Another good site that I send people to is TraVisa (link below).
http://www.travisa.com/
If you are really in a hurry for a passport (or renewal) you can check your lost post office (how I got mine quickly in a hurry).