I too do the number thing with digital clocks (I actually had to get an old fashioned clock with alarm in college because I was losing too much sleep staring at the numbers).
And I'm anal retentive about opening bags of chips, cereal, etc. - I HATE when the very far edges are still glued together, and I HATE when it rips down the side! I have a friend who opens bags along the seam down the back of the bag and it makes me twitchy, even though it's kind of cool that it forms a sort of bowl.
And I love house hunting too. I've helped more friends find apartments and condos...
I think my weirdest one is that I love researching products. If I get bored at work, I'll just go on amazon and find a random product, and start researching it. I research brands, features, options, etc. and then price compare across several sites, new and used, and then decide that if I were buying this product, I would get xyz. And then I close the browser and go about my business like the last three hours never happened. It's like window shopping for nerds.