Hello there, fellow addict!
I use several mods on top of the mighty GW mod. SH3 Commander (great "little" tool, and really handy if you want to ... say ... start a carreer directly in a IXD2, have the water a bit more translucent, get rid of fatigue, increase maximum tdc, etc), Ansacmicks(?) damage textures mod, fubar and hamburgers u-boat skins (and danlisas ... uhm ... alternative skin :rotfl
, sobers wave mod, etc, etc.
Modding is a long process of finding what you like, really. Its actually like going into a candy store and tasting everything, and from what I`ve seen there is no game with a better variety of mods than SH3.
Oh, get the mod enabler if you haven`t, this lets you change mods without messing up your install.