A colour picker for the web

We're thinking about creating a better web-specific colour picker for Typecast. The challenge is choosing the perfect mixture of features and the striking a balance between recognisable design patterns and a new way of doing things.

- What would you like to see in a web colour picker? RGBA? HSL/HSB?

- How would you like to see web-specific issues such as inheritance handled?

I'd really appreciate your input.