I found this site, and I think these cheatsheets are pretty nice: http://cheatsheet4oracledba.blogspot.com/2011/09/rman-commands-cheatsheet.html [ad#ad-post]...
I found this handy when I was working with two databases at work: http://download.oracle.com/docs/cd/B19306_01/server.102/b14196/backrest003.htm [ad#ad-post]...