Any tips/ideas on "molecular gastronomy".... without having to buy the equipment? Example: beet foam??

If you don't mind a small investment you can always buy an iSi whipped cream canister. The addition of 1% gelatin to any liquid will give it the ability to be whipped into a cold foam using the canister. That said, if you don't want to buy any equipment at all think of things in your kitchen that can already be made into foams. Powdered egg whites are relatively inexpensive and readily available. They call for water to rehydrate them but any nonfat flavored liquid can be used, like say, seasoned beet juice. Once re-hydrated you can easily whip them into a flavored meringue.

I doubt even Wiley Dufresne could come up with a recipe for "feet foam: LOL!! Interesting topic, I find it fascinating the link drbabs is great.

lol... didn't even realize I had typed "feet".... Thanks Babs!

Here's a molecular gastronomy website with a simple-looking recipe for beet foam. (You meant beet foam and not feet foam, right?)
http://www.moleculargastronomynetwork.com/43-recipes/Beet-Foam.html