You can get these in a variety of ranges. If you want to know how hot something is getting, slap one on! The number of people who fit additional oil or gearbox coolers without ever knowing if their oil or gearbox is actually getting too hot is amazing! For a couple of quid you can find out. I stick 'em on the inlet to the rad, sometimes on my oil filters, but I've seen them used in racing stuck to gearboxes, oil & fuel pumps, brake calipers, manifolds, hubs, driveshafts - basically, you name it!
Methods of attack
There's many, many articles, tips and instructional guides on the internet so I thought I'd add my favourites to the mix.
Asda / Tesco / Ikea £3 desk lamps are the worklights of the gods and I'll fight anyone who says otherwise!
Add an LED bulb and they're cool, bright, posable, take knocks and scrapes, and are so cheap they're disposable.
For larger areas, an LED-fluorescent-tube can be wired straight to the mains (no fitting) and provides an awesome interior light:
Loctite sell coppaslip, threadlock, thread sealer, etc. in little Pritt-stik style sticks which are awesome for keeping in the toolbox in the car.
These are £50 well spent on eBay, every workshop should have one - three spinners included seemed excessive but I'm not arguing!
The Laser flexi spinners are the best though as the ends are reversible for those fake Jubilee clips and fuel pipe clips with smaller drives.