What is this leak?

I just discovered a new leak, is this the transmission leaking? Do I have any hopes to get this fixed (preferably myself)? And to top this off, I noticed I have a small hole in the gas tank too, so there's leakage there as well, both these leaks must have appeared very recently since I was crawling under the car on Friday and didn't notice anything. And also.. The muffler has detached from the exhaust pipe (lots of rust). The car was fine just a few days ago, how can it possibly get this many new problems in just a few days.:help

Any help would be appreciated. I definately don't want to sell the car, it was such a bargain and I'm in love with it. But I don't have a lot of experience with fixing leaks and now I have two :'(. Am I best off getting these leaks fixed by a professional? The muffler is no big problem, I can fix that myself.

What is this leak?