Also, someone please explain to me how a 'side chain' is functionally different from an 'alt coin.'
The only one I used (and not much) was mastercoin. I had to run the mastercoin client on top of bitcoins to synch the 2 blockchains together and have mastercoin running on as a second client, constantly synching with btc's blockchain to produce a connected sidechain.
This enabled an exchange system of buy/sells for btc/msc within the mastercoin wallet much like a normal exchange which was quite impressive at the time (1 yr ago) but the project never seemed to go much further than that. Its using bitcoin as the backbone and other coins ride on it's back, you can create other coins easily of course within the so called bitcoin 2.0 environment and trade between them.
Additional: the more I think about it, the more its just another alt coin with fancy pairing abilities, you are right, lol.