What travel mistakes do you repeat?

MSNBC.com had a funny article called 3 biggest mistakes business travelers make. It made me want to write a vagabonder version.

Here's some mistakes I always make when traveling:

--Not having an electric adapter.  I never realize it until I have to recharge the batteries on my digital camera.  When I see the socket that's shaped differently and look at the prongs on my charger, I always start cursing my stupidity.  I've missed out on countless great photo opportunities due to this mistake.

--Forgetting my glasses case.  I don't know this until I'm about to go to sleep at my hostel on my first night and see that I don't have anywhere to put my glasses. I worry they'll get broken and ruin my trip.

--Not filling out the immigration form before my plane lands. Also related to this is not making a run for the immigration counters as soon as I disembark. Doing these two things would save me from those interminable waits in line.

--Not picking up a business card for my hostel as soon as I check in. Then I go out exploring the town and can't find my way back.  I've actually gotten better about doing this.

What mistakes do you guys make?  The ones where you curse yourself for knowing about but keep forgetting to fix.