You work in an office - an office much like any other - all of a sudden a hat-like object is passed around said office. You are invited to pick a name from the hat. You pick a name. You have no idea who this person is, you don't know what they like. You start to feel the pressure. What should you buy them? Stick to what you know - games. Or just buy them some deodorant, it's up to you I guess.
But we're sticking to the whole game thing. Typically office secret santa gifts range from $10-$30 gifts, so we've tried to keep it within that range.
SUGGESTION #1 LIVE points/PSN Voucher/Virtual Console points These work for a number of reasons. First off, if you can scope out what console the person owns, you can look all thoughtful/stalkery for knowing about the person you're buying a gift for. Secondly, these gifts can work within your budget, since you can buy different amounts of points depending on how much cashola you're allowed to spend.
SUGGESTION #2 Steam Sales! Unless your Secret Santa is one of those rubbish ones where you never tell each other who bought the gift, the crazy Steam sales that are occurring may just be your route to awesome presentage. There are plenty of games going cheap right now. Head to the Steam store for a full list.
SUGGESTION #3 Angry Birds Plushies Everyone loves Angry Birds. Except my wife who hates it for some reason. Regardless, these Angry Bird plushies have just gone on sale at the Rovio online store. They ship in December so they should get here in time. Just make sure and don't get the crappy boomerang bird. Because I hate that guy.