RJ45 is not a failed 1970's-era boy band. It's a "registered jack," the type of connector that hooks up phone and internet wires throughout a house. It's also very useful as a keychain rack, if you've got enough hookups.
Instructables user harari mounted several (disconnected) RJ45 hubs to a wall. Then, with the business end of some Ethernet cords, he fashioned a bunch of tech-chic key fobs. Now he can stash away spare sets of keys by "plugging in" the cords.
A step up from totally analog key hooks, this system keeps keys in place stays in place with the locking mechanism built in to the wires' ends. Plus it leaves you with awesome Ethernet plug key chains.
While we love the idea of constructing one from scratch, we think this might be a great way for renters to make use of spare phone jacks.
If you're able to disconnect power to the jack, you can use it as your very own keychain dock. Just find a cord that fits the plug, then follow harari's instructions on creating the male-end key chain.