1. A mobile USB Fan. These can be found all over amazon and are great.
2. A laptop carrying backpack. These are great and will not damage your
laptop. They also can serve as a great hiking backpack. The Swiss Gear
Scansmart is a great backpack I use.
3. A wireless mouse. The logitech m305 is an awesome and durable wireless mouse.
4. A portable computer combination lock. This will deter many from trying to steal a laptop.
5. An external hard drive. Storage space is so cheap now and it is great if you need to transfer files or if your main drive ever fails. Try the
external drive by western digital.
6. I assume you already have one, but if you don't, buy a flash drive.
7. A USB hub is great; it provides many ports when you need them.
8. A laptop cooling pad. This will make it more comfortable to sit on your lap and will improve the laptop's life span. I recommend the Targus Lap Chill Mat.
9. External speakers. Most laptop speakers are notorious for their terrible sound quality.Buy some logitech ones for almost nothing.
10. Finally, get a USB light. This will improve the brightness and allow you to see the screen
easier. A good USB light is made by HDE.