I've been toying around with this idea for a couple years now and I'm not as well versed in electronics as I'd like to be. The idea is to make a semi-small bracelet that uses an ID number to communicate to a tag, like a keychain dongle, and tells it to switch on a small electromagnet so the keys attach to the bracelet. The thought behind the ID number is so your bracelet doesn't activate your wife's keys instead of your own. Possibly NFC or bluetooth communication for low power usage.
Like I stated, I've been toying around with the idea for a while and I'm not proficient enough to use the KISS method (keep it simple stupid) and overcome overzealousness. I'd be more than happy to assist in any way possible and I live in Janesville, WI, so I'm only a short trip away.