I saw some 44oz bottles of agave nectar in my local health food store, and thought "hey, why not? I have an empty carboy, after all."
After dredging through the vast storage heap of useless trivia that is my brain, I recalled a factoid from my 8th-grade geography class.
The ancient Mexicans made a brew from the maguey called pulque (pronounced POOL-kay). It was a milky light-foaming brew, according to wikipedia. The maguey is a variety of agave. It's different from the blue agave, which is the source of tequila.
I plan on a few different experiments with it, since it's pretty inexpensive at $6.99US for a 44oz bottle.
I think a traditional pulque might be pretty easy, since it's just fermenting the agave nectar without adding anything.
The Tequiza option sounds tasty.
And then the full-blown mead/beer options might come into play once I have some idea as to what the stuff produces as a brew.