A New Magic
I'm currently developing a new product (which will be my first product, actually!), called "A New Magic," that is a mana-based system that uses slightly modified versions of the current D&D spells.
Spellcasters gain increasing amounts of mana as they go up in level, which allows them to fuel spells that they have "prepared." When they cast a spell, they retain it for future use, and can cast it over and over until they run out of mana.
They regenerate mana on an hourly basis based upon their Concentration score, and can "prepare" new spells at any time. I've also got rules for casting magic on-the-fly and applying metamagic feats.
I figure that this will appeal to people who are tired of the "fire-and-forget" system, but still want to retain the flavor of traditional D&D magic.
I'm just starting the playtesting phase, but if anyone is interested in more info, I'd be happy to let you know.