I'm a big fan of the Blastmatch and his little brother Sparkie. Both are ferro rods with built in sparking strips. What sets them apart is that they are used one handed so you can still use them if you've got an injury to an arm.

Can't say enough about the cotton ball and petroleum jelly tinder. Like the idea about the aluminum square, I'm going to try that.

I also carry a clear Bic type lighter (without childproofing), lifeboat matches in an orange waterproof case, and a magnesium/ferro rod bar. Guess I just like to make sure I'm going to get that fire started. However, since getting it, I've never needed anything other than the Blastmatch and PJ cotton ball.