I would also recommend an external hard drive for backups. Laptops are easier theft targets not only on the road, but also at home if (heaven forbid) you're ever burglarized. My laptop holds some "priceless" things (photos, papers and projects for school), and some things that would just be really inconvenient to replace (music, software). Keeping a running backup of all of that is at least a little bit of insurance, and easy utilities are available to basically handle it automatically.

I would recommend keeping a set of external computer speakers around too, if you ever plan to use the laptop for listening to music or watching videos etc. Laptop speakers are adequate--but not exactly satisfying--for music and such.

I've been laptop-only for nearly 6 years now and I love it. Knowing what sort of laptop you got might help inspire some more ideas.

Have fun!