Yes, I also got bored of wasting filament in useless cubes.

This is a simple 20x20mm cube with proper dice dots. And, by proper, I mean all opposite dice faces sum 7....
Dots are 4mm diameter and 2mm depth. "Letters" lines are 1x1mm So you can also test your printer accuracy.

Just for the record, remember the calibration formula:

(desired size/obtained size)*current number of steps per mm = new needed number of steps per mm.

In most printers, you can set this number on screen (remember to save it to the eeprom). In others, you can use Gcode G92 like this: G92 Xstepsxmm Zstepsxmm Ystepsxmm.
You can see your current G92 settings using Gcode code M503 and store settings with code M500.