I've used Wavehunters to go to El Salvador (great trip, stay at Casa del Mar, nice hotel right on Sunzal Point) and Nicaragua (Popoyo) both were great trips. Just my 2 cents.
Back before '05 and I grew up, We'd be planning trips for CR for 2nd week after Easter(Semana Santa) which is when their Summer vacation ends and the deals begin. The first 5 years went (91) Gogo tours provided great flights sometimes with car rental or 1st and last night stays in hotels. Problem with that is only travel agents could use them. Still good deals. Then after that, we'd find cheap flights and haggle when we got there.
Depends on where you want to go. Most of the time, I'm traveling with either my wife, or my whole family, so I start with Fodor's or Rick Steves books. Great travel books, especially if you're looking for more than just surf. I've used those two resources to surf all over France, Spain and Portugal. Of course, once you get there, you make nice with the locals and rely on local knowledge.
That sounds great, thank you everybody for your answers! I found a nice website, www.hostales.com which is in spanish and have great deals. Anyways, i will look for more.