MAME is strictly a non-profit project. Its main purpose is to be a reference to the inner workings of the emulated arcade machines. This is done both for educational purposes and for preservation purposes, in order to prevent many historical games from disappearing forever once the hardware they run on stops working.
Of course, in order to preserve the games and demonstrate that the emulated behavior matches the original, you must also be able to actually play the games. This is considered a nice side effect, and is not MAME's primary focus.
Aaron Giles has released the the latest official ’stable’ build of MAME. As of this MAME V0.120, Giles is officially producing a 64-bit native Windows binary along with the usual 32-bit builds to help encourage more testing of the 64-bit native code. For the most part, games run at least as well as the MAME V0.120 32-bit versions, and some run significantly better thanks to the architectural improvements of native 64-bit mode. Another notable change with this release is the movement of some core shared files in the source tree. A number of files in the mame/machine and mame/video directories were really more core shared components, and so they have been given a new home in the emu/machine and emu/video directories. Download MAME 0.120 (32-bit and 64-bit) at our MAME page
MAME - 64bit software
Latest version: MAME 0.163
Release date: 2015-06-24