Recognition and thanks
Many years ago, I remember helping out a distressed new user coming to my office. Her former coke head boss got his IT people to spam her new email address, signing her up to tons of junk mail lists, you name it.
I managed to completely stop it, and she thanked me by giving me a bunch of flowers. I didn't expect anything really, I just wanted her to be happy and not feel harassed by her awful ex-employers.
Other than that, I'd sometimes be treated to tea or coffee and even biscuits on my travels, but that was about it.
These days I'm at my desk a lot more in a supervisory role, so I don't get many gifts nor thanks coming my way these days. My staff do thank me if I've helped them out whether it's a work or personal issue, and that's good enough for me.