Izarc is also good for those .rar files.
http://www.izarc.org/download.html
I'm a SHIII noob, so not quite ready for RUb 1.44. RUb aside, the Increased harbor traffic mod (standalone version) seems essential to me. Going in and out of the harbor is so cool now I never do it in time compression any more.
http://u-boot.realsimulation.com/
The improved smoke mod (I'm using the one that comes with Improved U-boat) seems pretty essential as well.
I'm also using the "Crew Vitamins" mod because it seems unrealistic to me that the crew would poop out after just a few hours of duty.
The many, many graphics mods are good too ... just added a sub skin (paint job, that is) for my latest patrol...
Have fun!