FITNESS TRACKERS
Headlamps: Headlamps let you keep the urban exploring going long after sundown. I have this basic Petzl model, which I use for hiking and camping. When buying a headlamp, just make sure you get one with >50 lumens, so it's bright enough to see on the darkest nights. If you want a detailed buying guide for headlamps, check out this one from REI.
The great thing is that you can prevent reactions from these plants even after exposure with something called Tecnu. This product wipes away the urushiol oil that causes the reaction, and keeps you away from annoying (and potential harmful) rashes. I buy 50-packs of the stuff like this: Tecnu Oak-n-Ivy Cleanser, Box of 50 0.5 oz. Packets and throw a few packs in my bag before every hike.
CLOTHING
Clothing is very personal, so I'm just offering two ideas here that should work for most people. Scarf with built-in insect repellent: I am lucky—when I'm in the outdoors, mosquitos leave me alone. But I know most aren't so lucky. I don't personally need this item, but received one for free, and I just love it because it's really cute! The clothing includes Insect Shield® repellant and you can even wash it up to 25 times.
We created a new line of urban hiking-themed t-shirts that help you show off your love of SF. T-shirts either feature our logo or our favorite SF landmark, Sutro Tower.
BOOKS
And of course I need to suggest my book, Urban Trails: San Francisco! If you want to explore not just stairways, but also the 70 miles of hiking trails that San Francisco has to offer, this is a great book for you. The book includes 50 different routes, 40 right in the city, 6 north of the city, and 4 south of the city.
To be fair, I do not have this book yet: 111 Places in San Francisco That You Must Not Miss
I'm going to stop here with the books, but could mention so many more! Maybe I'll do a whole post on books for urban explorers. :)
MISC.

Urban Hiker SF Gift Certificates: Gift Certificates are available on the Gifts & Merch page of our website. Gift certificates are sent to your recipient—or you—instantly, so they're great for even the most last minute of shoppers.
I hope you've enjoyed this holiday gift roundup for hikers. Happy Trails and Happy Holidays from Urban Hiker SF.