I'm not the type of person who carries a prison warden-style set of keys. I've been using the KeySmart key organizer for over a year and it's helped keep pocket clutter to a minimum. It reduces a set of keys into something resembling a Swiss Army knife and is far less bulky than than a regular keychain. It's like the difference between carrying a roll of pennies or a bunch of loose change in your pocket.
I've been using their newest model, the KeySmart Pro (pictured above), for the past couple months and highly recommend it. It adds some useful features, most notable of which is its Tile functionality. The KeySmart Pro also includes an LED flashlight and a Micro USB port to charge the device. Unlike regular Tiles, this one is rechargeable.
The additional functionality does make the Pro model bulkier than the original KeySmart as it has a plastic shell to encase the electronic components, but it's hardly noticeable. Without any keys attached, it's extremely lightweight.
The KeySmart Pro is a great idea executed well. Many Tile users are likely to have one on their keychain (I used to have one attached to my KeySmart) so combining both together makes perfect sense.