I have an old COROS and picked it precisely because it's not much more than damn good running watch with a battery that lasts for weeks. It's definitely not necessary for road running, but I needed it for unfamiliar trail running routes.
Donating technical skills with a market rate of a couple hundred bucks an hour can add up much more quickly than donating cash in many cases. And it doesn't have to be a massive investment - in a few hours you can make a much more manageable and better looking website for a lot of organizations that can't afford to pay for one.
I know an individual from Microsoft who's managers were kind enough to allow him a 6 month absence to hike the PCT. He thru hiked it this Summer and is now back on our team, as productive as ever.
I'm sure this situation isn't exclusive to Microsoft. If you're valued as an employee and want to do something like this, make your wishes known to your management and see if they're willing to work with you. If you never ask, the answer is always no.