Couldn't find a topic for this, so I figured I would create one!
Now, vanilla Diablo 2 is decent. Boring, predictable, but a solid game. I recently wanted to get back into it, but the pace of it is so horridly slow (especially on ladder) and playing with any character editor tools takes the fun out of earning gear.
And then I found this:
http://modsbylaz.hugelaser.com/Median XL is as close to a total conversion of Diablo 2 using the game's engine as you can get. It's probably one of the best mods out there (and relatively easy to install/uninstall as well); it completely revamps all the classes skill trees, and also revamps the difficulty to go with it. There's little documentation ingame, but there is a forum up, and the main site has a majority of good items/combinations/etc.
Unfortunately, Median XL doesn't have its own "official" realm. Enter D2Maniacs:
http://www.d2maniacs.org/It's based in Germany, so it's a bit laggy at the best of times (and unplayable at the worst, but that's only occasionally) but it acts as a persistent ladder and replacement for Battle.net, at least as far as Median is concerned.
Finally, if you're on Windows 7, fear not! There's a couple things you can do to make it work (even on 64 bit, which I currently used, albeit with UAC turned off). There's also some tips and tricks that may apply to other users.
"C:\Users\Public\Games\Diablo II\Diablo II.exe" -skiptobnet [Example of my shortcut; -skiptobnet skips the initial movies and automatically starts connecting you to Battle.net once you click the shortcut]
Right click the shortcut -> Compatibility tab: Run it in XP Service Pack 2/3 mode (I currently use SP3).
Check Disable Virtual Themes, Disable desktop composition, and Disable display scaling on high DPI settings. This should allow it to run without errors (provided you installed the game and updated it correctly)
http://www.svenswrapper.de/english/index.html - Sven's Glide Wrapper
This neat little .dll allows your game to run in 3DFXGlide mode, even if it isn't completely supported by your video card. Read the site for details; I've never seen something that makes the game run faster/look better in a long time. You can scale resolution and change certain things that you otherwise wouldn't be able to in the default Diablo 2 settings. Personally, I love it because it eliminates the weird colors that sometimes came up when a video played or after tabbing in/out to check something.
If you have questions, comments, etc, post! If you do decide to play on the D2Maniacs realm, my account there is AstralVoid; there was a reset recently so I haven't quite climbed back to level 120 yet, but I'm always happy to help.