Oh come on, those sticky threads are NOT a good place for a first time DW player to find out about the current two top mods. In fact, that's what the 'The DW Mod Scene - Ok, WTF?' thread is all about and the situation still hasn't been resolved. We need ONE sticky with a simple list of the mods for DW, a brief description and their download links. Seriously, I think I might just have to do this, although I am not a modder and really don't know if I'm aware of ALL the mods available.
mobius22, to answer you question broadly...
LWAMI 3.10 (LuftWolf and Amizaur Weapons and Sensors Realism mod)
This is probably the oldest and longest run mod out there. It's a realism mod that is fully compatible with all original missions and almost all user created ones. A very good and complete mod.
RA or DWX 1.1 (Reinforce Alert/Dangerous Waters Plus)
This mod is relatively new and extremely sophisticated. It is a realism mod (though different in some respects from LWAMI), but goes much further. It mods the actual game engine and adds a number of new playable platforms and weapons. While it attempts (and to some degree succedes) to fix many of the bugs inherent in the game, it has a few well known ones of its own. Certainly a great mod, but still barely out of its beta testing stage.
AT3 (Alfa Tau 3)
I really don't know much about this mod other than it's based on an older version of LWAMI, but adds new playable platforms.
Drifter mod (used to be called Sakura mod)
I have to confess that I haven't tried this one yet. Some of the Sakura mod features were incorporated into LWAMI 3.10, but I think the newly released Drifter mod has some new stuff to add. I'm pretty sure it's supposed to be used with LWAMI, but I'm not positive.
As a side note, both LWAMI and RA add a number of new countries and a hell of a lot of new AI platforms into the game, but like the realism features, they are a bit different. Also, scenarios created specifically for RA/DWX will most likely not work in the unmodded game or with any of the other major mods. This is also true with LWAMI 3.10, but not as often.
Pretty much all the mods can be downloaded at the CADC (Commanders Academy & Dive Center) located at:
http://www.commanders-academy.com/forum/
It's a bitch, but you have to register to download files. It's free and really takes about five minutes (and you don't need to provide any personal info), so it's worth it. Any mod not available there you can find in the DW Mod Workshop, but I gotta say, it's sometimes not that easy to find them. Yeah ... that forum is really not a good reference for anyone who just wants to use the mods and not argue about them or try to mod themselves.
Hope this helps