In my eagerness to see what other ditros bring to the table I've installed a few, and I would like to free up that space on my drive, but when using gParted I can't tell what is what, and I don't want to mess up my current install.

How can I tell what is installed on which partition? I tried df, but it only lists the mounted partitions, and fdisk didn't show anything, ls -a /dev/sda* didn't give any helpful info either.

I have Ubuntu 12.04 as my main install, with Pinguy and a couple of versions of some offshoot of Ubuntu as well. I would like to remove the Pinguy and off-shoots, but don't know which partitions they are on exactly...especially Swap and boot partitions that I don't want to accidentally lose.

Any help is greatly appreciated,

Gparted will not (AFAIK) let you modify partitions that are in use (e.g. root, boot, home...). It should also show which partitions are swap.

In grub, you can find which partition is the root for a particular distro by highlighting the disto name and pressing e. The line beginning with the word kernel should have "root=" followed by the root partition.

You could also try mounting the partitions:
You can't mount swap, so this will help you find the swap partitions.

If you are able to boot each of your systems and are using the Grub bootloader of Ubuntu, they will be listed in the menuentry by partition.
You could also mount each partitions / (root of the filesystem) partition and look in /etc/issue.