Running R inside a buffer in Vim
Another option, and forgive me for pointing you back to EMACS,
viper-mode
http://www.informatik.uni-hamburg.de/RZ/software/emacs/viper/viper_3.html
It's an EMACS mode that makes EMACS feel more like Vim, while giving you full access to the wonderful, mind-boggling complexity of EMACS if you ever want it.