Gray's anatomy for injections
http://www.bartleby.com/107/illus827.html
Gray's anatomy is online for all that are interested.
http://www.bartleby.com/107/
Here's for the posterior leg....for the glute guys out there...
http://www.bartleby.com/107/illus832.html
There are much smaller nerves that branch off of those pictured as well. I'll try to find a good image.
Actually, this one is really good:
http://www.vh.org/adult/provider/ana...ection/01.html
This is about 1/3 of the way down the thigh and will show most of the major nerves the best, being at their thickest points in the leg.
Happy poking.