Green Lizard,
Lithium Ion and Nickel Metal Hydride do not have memories, just Nickel Cadmium.
If you flatten a battery before you recharge it - some people flatten their batteries manually, and some chargers do it automatically - you greatly reduce the life of the pack. A given battery pack may last for 500 full cycles, or 2000 partial ones. If you're fully flattening the battery by actually using it, then fair enough, but do not do it as part of your recharging ritual.
"Memory effect" is now used as a general term for anything that makes a battery not deliver its full capacity. What the term originally referred to, though, is a phenomenon that's probably never actually been observed in consumer hardware.
True memory only happens in sintered plate NiCd cells (which aren't necessarily the sort of NiCd you're using, and are of course completely different from any kind of NiMH cell), and it only happens when you precisely discharge a cell to exactly the same level over and over again, and recharge it without any overcharge. True memory effect happens in satellite power systems, electronics test labs, and practically nowhere else.
Take Care,
Richard