T-shirts, stickers, maybe the gift bag itself could be like a 'bum bag' (USA people call them a fanny pack? whatever - they go around your waist and have a small compartment to carry stuff in.)

I got a "keyboard calendar" at a race recently...it sticks on to the top of your keyboard and is approximately 15 inches wide by 1.5 inches high. It's been right here in front of my face since January and has the name of the sponsoring organization on it. It has a calendar for the whole year, which comes in handy a lot. Way better than a mouse pad, and almost everybody has a computer. They must be pretty inexpensive as well.

In my racebag today, this is what they included.... a nice calculator!
http://www.sunscope-asi.com/cgi-bin/webc.exe/st_prod.html?p_prodid=48&p_catid=3[/URL" target="_blank">
PB

I've never actually seen one of these but thought that it might be a good idea and be in a comparable price range to water bottles -- probably even cheaper:

How about large plastic cups with proportions for smoothies printed on the sides? (Much like the glasses you see with measurements for mixed drinks.) This would work well for measuring out what goes into the smoothies, pour the contents into the blender and once blended, pour back into the cup, very useful. Many runners would be likely to use them daily. You could have 3 or 4 different smoothie "recipes" along the sides and of course your company's logo on there. I'd bet that most runners would be pleasantly surprised to find something a little bit different in their gift bags. Many of us drink smoothies and even if we don't we can use the cups anyway.

(And if you plan to sponsor the race annually, you can always just use different colors and print different "recipes" each year.)

hand towel