This is already a very old case of abuse. In 1997 I was totally into BEAM robots and for a build I needed a H-bridge but I couldn't find anything in my toolbox that fitted my needs till I found this one and thought just give it a try.
The 74AC139/ACT139 is a high−speed, dual 1−of−4 decoder/demultiplexer but could it be used as a H-bridge? In fact it worked out beautifully. It turned out to be an all-in-one, fool proof H-bridge for driving up to 300mA motors between 2.5 and 6volts. And as the 139 is stackable and symmetric, all input and output leads can be folded over from one side of the chip to the other to increase the power capacity.
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Details
More details and user experiences can be found at the Solarbotics site and my personal page.