Here's an atypically short review from me, but I may add some photos or details when I'm home... for now I'd like to compliment some of the recent (Feb 2012) reviews, as the Myaka I know and love is so well described.
Some nice photos I see now are of the "Canopy Walk" where one can climb up an internationally-constructed tower, across a plank bridge, and up to the tree line overlooking birds and other wildlife. The description of the easy access to alligators is spot on, as one can drive straight ahead from the State Park entrance, past some trails which are also worthwhile walking (especially to commune with nature and/or do nature photography, as I've often done - photos to follow). One reaches a bridge where typically you'll see cars pulling over to the roadside, and people get out to enjoy the wonderful view of the river and a marsh area with abundant bird life. On either side of the bridge, in the water, almost always (weather conducive) one sees some rather large alligators, either floating or sunning. Sometimes there are kayakers going by too, past the gators. People fish too, and read the signs about not feeding or "molesting" the gators - both against state law.
Further up there is the old/original and also a newly constructed restaurant/gift shop where you can get alligator gumbo as well as ice cream, drinks or gifts post cards, hats, souvenirs, etc. If you park at the end of the road near the old gift shop, to your right in the marsh leading into the lake, you'll see the river/fan boat ("Gator Gal") on which you can take a tour and see gators, wild boar, vultures, and other various local nature.
There is also a land tram, and one might see deer, armadillo, and hundreds of bird species (including at scenic picnic areas along the extensive road system.) This park is one of the largest in America - huge, bequeathed by the legendary Palmer estate to Florida as a gift of Old Florida, to be preserved and enjoyed.
I've not camped here, so can't add anything to the comments. It is a state park, with the usual permits etc. required for camping, and also for some off-road hiking access, which I have done - leading to the far side of the Lake, with legions of alligators, herons, & vultures (one sign warns of parking in one place, as vultures may eat tires!). As others have said, this is real nature, and real wild, no safety rails in some places alongside things like marshes with alligators - so parents, keep your children close! Be safe!
Well, these are the highlights for me. I've tried to go to Myaka every year for decades now, still my absolute favorite "therapy" or meditation tool, along with long walks listening to the sounds of nature, and snapping some photos too.
A treasure. Reasonable fee (park entry, per car), lots of things to do, from a boat or tram tour, to walking, picnicking, camping, hiking, and bird-watching - from the ground or treetop canopy. Enjoy!