Anybody know?

I'm assuming you mean "GENERAL ISSUE" Because for instance the S.A.S. uses them on a limited basis. Here's the one's I can think that use versions of the M-16:
Philipines, Canada , Mexico, Kuwait (at least I saw some) United arab emirates, and several other nato countries I can't think of just now.

Isreal. Don't you watch the news?

British Army used it in Borneo, Israel, Canada, PI, Japan(maybe)

Australia: M16A1, M16A2 and M4A1
Canada: C7 and C8 variants
Central African Rebublic: M16A1
Chile: M16A1, possibly M16A2
Colombia: M16A1, M16A2, M4 and M4A1
Denmark: C7 and C8 variants
El Salvador: M16A1
France: M4 variants with some SOF units
Greece: M16A2s and M4s
Guatemala: M16A1
Honduras: M16A1
Indonesia: M16A1
Israel: M16A1, M16A1 carbines, M16A2, M4 and M4A1
Jordan: M16A1, M16A2, M4 and possibly M4A1s
Korea, Republic Of: M16A1
Kuwait: M16A1, M16A2, M4 and possibly M4A1s
Lebanon: M16A1
Liberia: M16A1
Libya: M16A1
Malaysia: M16A1
Mexico: M16A1, M16A2, M4 and possibly M4A1s
Morocco: M16A1
Netherlands: C7 and C8 variants
New Zealand: M16A1, M16A2 and M4A1s
Nicaragua: M16A1
Norway: M4A1s or C8 variants
Oman: M16A1
Panama: M16A1
Philipines: M16A1, M16A2 and M4s
Poland: M4A1s with SOF units
Singapore: M16A1
Taiwan: M16A1
Thailand: M16A1
Turkey: M4s and M4A1s
Uganda: M16A1
UAE: M16A1
UK: M16A1s, M16A2s, M4s and C8 carbines
USA: M16A1, M16A2, M16A4, M4, M231 and M4A1s
Uruguay: M16A1
Zaire: M16A1