Are you a red kapitan? If so you need crazy Ivan's Russian sound pack. It gives all Russian boats real Russian crews, not people with bad Russian accents. You'll have to do a little work to get the sounds in game, but I promise it's very easy, it sounds like more work than it is.
Also, are you a kilo kapitan? If so you also need the binocular and periscope reticules.
Binocular reticule:
http://www.subsim.com/radioroom/showthread.php?t=126588
Periscope reticule:
http://www.subsim.com/radioroom/showthread.php?t=126344
Have a look around the downloads section here:
http://www.subguru.com/
You can find crazy Ivan's Russian sound pack there. Not to mention there are alot of scenarios there.
