I got D2Multires from Moddb. Instructions are in the comments. Since Diablo 2 is sprite based everything gets smaller and smaller as you increase the resolution. However if you find 1080p too small, then you can still enjoy widescreen at 720-900p and even at 720p it plays a lot better than 640x480 or 800x600.

Hopefully they release the original and re-master at the same time, then make one of 'em free, like they did for Shadow Warrior ahahaha.