We use EWAH (another compressed bitset from Daniel Lemire) heavily at work to store inverted indices in a compressed form. Apart from lowering the memory foot print (vs storing sorted integers), AND/OR operations are much faster when you want to do stuff like intersecting 2 bitsets to find the overlapping members etc.
You should checkout some of the other impressive compression related stuff that Daniel has open sourced: https://github.com/lemire
You should checkout some of the other impressive compression related stuff that Daniel has open sourced: https://github.com/lemire