This is what I did for fun:
I took some super bright blue LED's I got off e-bay and wired them up to the bottom of my Tau Empire Devilfish for Warhammer 40K. In you are not familiar with the unit, Devilfishes are skimmers. This means they hover above the battlefield and I wanted to create a cool looking glow for this hover effect. A total of six LEDs are used and two AAA batteries in the troop compartment provide the power.
For our hobby electronics friends:
Each LED consumes 1.2 volts of power and they are wired in parallel with a 100 OHM resistors. The current consumed by each LED = (3-1.2)/100 = 18mA. With all six on that is total draw of 18*6 = 108mA.