You're welcome. Wizards of the Coast put a lot of stuff out on the net. You can find a (mostly) complete list here (note that the most up-to-date listing is currently on page 5).
There is still room for this class if you want to work at it. Prepared/prepared (only Wizard and Wu Jen, I think) and spontaneous/spontaneous don't have any class to progress them (although UM has an adaptation for that). If you spruce it up a bit, or make it more specific or something, you can still carve out a niche for your idea. Take the Arcane Hierophant (RotW), which works like a Mystic Theurge designed for arcane/Druid instead of generic arcane/divine, or the Green Whisperer (some Dragon magazine), which deals with Bard/Druid.
If you do continue to develop this, I cannot stress the need to reduce the requirements on the spellcasting side of things. 3rd level spells from two lists requires a serious commitment (Wizard 5/Wu Jen 5 gets it the earliest) if you don't want to use early entry tricks. Being 5 levels behind on spellcasting ruins your spell access compared to just going straight caster. Even the 3 levels lost for Mystic Theurge amounts to a price that's usually too high.