Forgive me if I'm duplicating advice already given...

*An ISP with plenty of dialup numbers in plenty of cities, and a wireless card to hopefully avoid having to use them.
*Bills that are paid with automatic, scheduled debits or online payment systems.
*A bank with a very good and very user-friendly online or phone-based 'teller'.
*A bank that offers good rates for currency exchange - most do, but some charge outrageous fees for pulling cash out of foreign ATMs. (Also, some banks that are low on services, such as small credit unions and the like, may not allow you to use ATM machines outside the US.)
*Small ear plugs and eye shades. The Bose noise cancelling doo dads are nice, but bulky. Sometimes you really just want to travel light.
*A Barnes and Noble card - discounts on the books you'll buy to keep your travel time occupied.
*A travel wallet for your passport, hotel and airline cards, discount cards, etc. Get duplicates of the bank cards you use often to prevent having to move things around before your trips - and keep a credit card that you rarely use in this wallet to be prepared for mid-trip emergencies. Also keep photocopies of your passport, drivers license, itineraries, credit card and bank phone numbers and account numbers, emergency contact numbers and other important documents in your suitcase, in case this wallet is lost or stolen.
*A small inflight survival kit: bandaids, a couple of small single-use packets of neosporin, a small pill box containing a few essentials like ibuprofen, sleep aids, decongestants, pepto/immodium. Antibacterial wet naps (purell makes some good single-use packets, and you can buy them in bulk at Sam's Club). You might ask your doc for some antibiotics in advance and advice on when to take them/not to take them for certain GI ailments common for travellers. It's nice to have them readily available if needed. It's easy to let this kit get out of hand - but only pack what you'll need to have readily available. If you're sick, you can pick up more items later - but you will be glad to have your first couple of doses on hand. Also toss in some of those facial cleansing cloths - they're nice to have to freshen up with in the middle of a loooooong flight. Listerine Pocket Packs and those new OralB 'BrushUps' are great for keeping a fresh mouth on long hauls.
*An Eagle Creek packboard - you can fit a lot of clothes in these things, and keep them relatively wrinkle-free. Using the packboard compresses your clothes, and frees up space in your suitcase for other items too.
*A good, workable toiletry kit. The good ones don't take up much space. (I like Eagle Creek for these too.) I find it invaluable to be able to have all of my bathroom items in one little bag, rather than having multiple items floating around my suitcase. Get to the hotel, put your little bag in the bathroom, and you're ready to go - and having things altogether makes it less likely that you'll lose things too. Also stop by the camping store and pick up some small bottles - if your one of those guys who doesn't like using the hotel brands, or needs certain things, carry small quantities instead of the whole bottle. I'm always amazed at how many people carry a huge, full bottle of hair gel when they're only planning to be gone for a week! Same with hair dryers - they're in most hotels. If you need one, call ahead and see if your hotel has them before you pack it.
*Durable and comfortable all-purpose shoes! If you can find shoes that can take you from the airplane, to walking around sightseeing, to getting semi-dressed up for a night out, etc, then your packing gets easy. Shoes take up a lot of room in a bag, so think multi-purpose when you can.
*Another plug for Eagle Creek products: I carry one of their small pack-it bags for my undies and other intimate items. When TSA or customs wants to search your bag, it's comforting to know your 'untouchables' are safely packed in their own see-through bag.
*Get a spare battery for your cell phone. Most importantly, get a second phone charger - this keeps you from having to pack it every time you leave for a trip, and from missing calls due to a dead cell phone when you leave it in a hotel room (and you will, at least once).