What about implementing a bitmap index? Any use cases?

Hi,

I know there exist Bitmap Index Scan and Bitmap Heap Scan in Postgres.
What about implementing a bitmap index for explicit use (CREATE INDEX ...)?
Any use cases?
Bitmap indexes work best on values with low cardinality (categorical
data), would be efficient in space and ready for logic operations.

Stefan

P.S. Disclaimer (referring to my other thread about Hash): I'm not a
btree opposer :-> I'm just evaluating index alternatives.