I'm actually running a campaign right now, centering around Tiamat as the creator of the world and all life. Poor misunderstood goddess.
In the campaign I am running Tiamat is the mother of all dragons and is angry at then being usurped by other races. She is not evil at all. She is lawful neutral and believes that the world would be better off if law was strictly enforced.
Lloth is also in my game she was an elven god betrayed by Correllon and Selune so she made a pct with a demon and became one.