CutmanMike's multiplayer Doom mod Mega Man: 8-bit Deathmatch is still a ways away from release, but to keep you entertained till then, here's a video exhibition of every usable weapon the final game will have to offer. A detailed description of how each weapon works available here.
For the uninformed, 8-bit Deathmatch is a custom Doom mod developed by CutmanMike that "aims to put Doom and Mega Man into a blender and spew out a fun new way to blast your buddies online." The game is rendered entirely in 3D, with textures based upon classic 8-bit Mega Man sprites. You can play it solo in single player or duke it out online with other players.
A demo of the game is available for download via this link. This version contains includes four maps, five playable characters and ten weapons. Enjoy and look forward to the full game soon!