Steve's tutorial on 4-Quadrant control was great.

OK now for some drivers for DCmotors :

With National's LM3524D plus LMD 18200 you can drive upto 3 Amps motors, reverse and set the operating level also.

With SG's LM298 you can drive upto 2 Amps.

Both the above are H bridge applications.

For more information please download the data sheets from the relevant web sites.

Good luck

Raghu