it depends on what you are looking for.
AABattlemap is a great utility that provides a map and units etc, for Axis and Allies. It does not however provide a place/lobby to find other online players. For that part you will have to either use the forum to find players, then play by forum. Or you can try out TripleA, which provides both, at http://triplea.sourceforge.net/mywiki
and can be downloaded http://www.mediafire.com/download.php?wzvnmlw1uej
for the latest version, and for an earlier version http://www.mediafire.com/download.php?wn3mjmen3yk