Here is a list of all the different Nintendo 64 ROM Formats.
Normal ROM Files
.bin
.jap
Used to indicate ROM dumps of games released in Japan, in any format
.n64
Indicates ROM dumps stored in little-endian byte-order
.N64
The Extension used by the makerom utility of GCCexe as part of the official SDK. It's in the Big Endian format: NSME (Nintendo Super Mario English) Address(hex)|-3B-|-3C-|-3D-|-3E-| Value (hex) |-4E-|-53-|-4D-|-45-| Value (Ascii)|--N-|--S-|--M-|--E-| .pal Used to indicate ROM dumps of games released in Europe/Australia, in any format. .rom .u64 .v64 ROM dumps produced by or compatible with the Doctor V64, with data stored in a byte-swapped version of the N64's native byte-order .usa Used to indicate ROM dumps of games released in North America, in any format .z64 ROM dumps produced by or compatible with the Z64 and the Retrode, with data stored in the N64's native big-endian byte-order
N64 Dynamic Drive
.d64
n64mdisk (SDK) output format. Big Endian.
Other playable formats
Some emulators can play ROMs that are within a compressed .7z or .zip file.