View everything right here: http://www.sethsbikehacks.com/gifts/

Allen Key Sets: http://www.sethsbikehacks.com/gifts/#hexkeys
Multi Tools: http://www.sethsbikehacks.com/gifts/#multitools
Floor Pumps: http://www.sethsbikehacks.com/gifts/#pumps
Socks: http://www.sethsbikehacks.com/gifts/#socks
Tool Sets: http://www.sethsbikehacks.com/gifts/#toolkits

Here are some gifts that you can get for any mountain biker, regardless of what type of bike they have, or what type of riding they do. It turns out that most of these fall under the categories of accessories and tools since these will pretty much work for anyone.