Keybrid cleverly collapses the key and keyring into one pocket-slimming package (that also works as a money clip, if you so desire). We take slimming down bulky keychains and wallets pretty seriously around here, and we kind of love it.
There's not much more to it than meets the eye; it's really simple, but it's also very clever. Why not collapse the two into one? You can grab a Keybrid for $US9 from their store (making it a nice stocking stuffer), or if you're feeling more in the DIY spirit, you could easily make your own with a bit of cutting and soldering. Either way, it's a fun idea, and one likely to slim down your pockets. (Ignore the sillier aspects of the video — you'll probably never ever use it to blow bubbles.)