7806's do exist. (I'm looking at one right now.)
LM7806 or 78M06. Easy 6VDC.
Data Sheet:
http://www.htckorea.co.kr/data/LM78XX.pdf

Probably the best solution would be an LM317
and two resistors forming a voltage divider to set
the output voltage. One could use a single trimpot
as well. Then you could set any voltage you want.
Don't forget to use bypass caps on the input and output,
and a heatsink.