Standard (and most common) USB Male Connectors
In general, the A types are used in hosts (computers), and type B in slaves (devices).
In big hardware (desktop PC, printer) normal type is used (A and B, respectively). In small hardware (laptop, camera) the MINI type is used (Mini-A and Mini-B, respectively).
"Semi-Standard" USB Male Connectors
Nevertheless, a number of other non-standard USB ports/connectors are used in small devices like portable mp3 players eg. the s1mp3, usually in slave mode (so, like a "non-standard Mini-B").
Here are some examples:
Now, it seems like 99% of small devices use the standard Mini-B or the "Aiptek" Mini-B, this last one being the case of some(or most of ??) S1mp3s.