I consider this question different from others because of the variety of things I need this setup to be able to do.
Description: I want to build a minimalistic motor controller capable of controlling the speed and direction of 2 servos and 2 brushed dc motors. That is to say that I have size and weight constraints that I do not think would be satisfied by off-the-shelf solutions.
The Problem: I have an arduino board (all/any model) that can only output 40mA per pin which is not enough to power even the tiny dc motor I am using. If I power the dc motors directly from the 3.7v 150mA/h 25C LiPo battery it seems to spin at the top speed I need to be able to achieve from the arduino. I need to be able to controller the speed and direction of each of the motors from the arduino PWM output using power from 1 or more LiPo batteries. The battery I have came with the motors so I know it can power them.
Story: I salvaged the motors and battery from a small rc heli and I want to rebuild it as a UAV replacing the onboard chip with my small arduino (pro mini or teensy).
Update 1: Apparently I may have been overcomplicating the problem and a simple H-Bridge is all I need. I will post back if this turns out to be the case. Thanks for the helpful comments. I will upvote once I have enough rep.