Brew their doppelbock recipe (with 2 containers of Oktoberfest), buy an extra pack of hops, and some dry lager yeast. If you don't have a lager fridge yet, start looking on craigslist, I got mine off there for $50.
Sorry, I got nostalgic the other day and actually looked up how Mr. Beer was doing. They're getting into some interesting stuff. I still wouldn't want to try brewing with their extract again, though.
I was not a fan of their porter, but I bet adding some blackberries would make it more interesting. If you can find a fine mesh bag, sanitize it and use that to contain the fruit pulp when you add it. I made one of their recipes with pumpkin and each bottle ended up with a little pumpkin pulp in it. Didn't taste bad, but it made it look like crap.