This is your man for everything!
http://www.getlostincostarica.com/Ge...osta_Rica.html
The guy who owns this company is Don - he is 1 man show, very cool, trustworthy, and is the source for any info you might want. He is local to Tamarindo. We did a trip to Ollie's / Witches with him, and we paid as much as a 1/2 day everywhere else for a full day (fully legit w/ permits and such too). I guess the fact he is a ripping surfer helped that day...considering it was going off! For the zip-lines definitely do the canopy / canyon tour up at Rincon. It's the closest volcano to Tamarindo, and only about 2 hr drive max (it's pretty close, just the roads are SLOW getting up there).