Define software? If you're talking about frontends, the big two are Ride Runner, and Centrafuse. OpenMobile is rapidly getting larger, and will likely eventually be considered one of the big ones. Look in the Frontend section of this forum. There is a huge list of available frontends, most of them small and still under some development, but those are the main ones.
There is also a variety of other misc. software that is useful. Here are some links for you to check out:
sorry, the right frontend is the one you are happiest with, your gonna have to put some effort into it, didn't mean to belittle you, but this comes up often with newbies.
I use RR, and understand that I have to put a lot of time into it to get the functionality I'm looking for. I hear Centrafuse might be an easier entry into the hobby, and I do believe that OpenMobile just may prevail in the end as the best PC based frontend.
And then there is the whole tablet question....
TruckPC - gutted, being used for test setup
BoatPC - All in 1 in cuddy, N7 using VNC on dash, RR
BlazerPC - Nexus 7 with Timur's USBROM