I have personally spent a couple of years traveling and the gadgets I most used were a 12 inch powerbook and a GSM mobile phone. The laptop was great and being the 12 inch was pretty light. Internet cafes can be uncomfortable, spyware infested dives. Having your own laptop means you can at least try and be secure. The phone is also good. Just buy a SIM card in each country you are traveling through and the price becomes pretty reasonable. They can be a godsend for booking places while you are on the moved and can save you time hiking from hostel to hostel.

Security can also be an issue but if you have your own room you can normally leave the laptop in there. Try and find a good hiding place for it. Also make sure you get a good daypack that has a laptop section in it but doesn't look like a laptop bag.

Oh and a camera. Take whatever you feel comfortable with. An SLR is great if you love taking photos but can be a hassle to carry. I personally have a great camera on my phone (Nokia N73) and by girfriend carries the SLR.