I just stumbled across a recently released application. No only is it free, its OPEN SOURCE! I haven't found a good flash card app yet for my G1 (soon to be HTC) but this open functions great. I wasn't sure if any one else out there has extensively used it or checked out the code but I haven't ever seen one that lets you input Mathematical symbols or use Text to Speech. Its name is StudiDroid and I hope the developers release frequent updates!