Try Google “pixel font”.

> I am looking for some really diverse sans serif fonts (extra light, light, condensed, roman, bold, caps etc…) that are legible at small sizes on the screen (7-9 points).

This is hard (some would say impossible) - unless you have ClearType (or one of its clones) activated the best you can do with bi-level rendering is have one or two pixel stems which means a maximum of two weights.

7, is that seven? Even if you have CT, I doubt it’ll help. 8 a little. 9 a little more. Stylistic diversity at those sizes is not a problem because it’s not really possible. Have you ever done this before? :)

Perhaps it could be alpha