As Angie said, Aqua di Gio is a classic.
I find Gucci pour homme and Burberry Touch pretty easy to carry too... Not to mention Eau d'Issey pour homme.
If you ever come by a Comme des Garcons 2 Men, it's one of my favourite pour homme scent, though I must admit it's very woody... Same goes for Helmut Lang (slick, sophisticated but quirky)... Try those two if you are looking for a "signature scent" -^_^