Life In 19x19

Is there any software to analyze a game? For example, I'd like to enter an sgf file which ends with a resignation and then watch a go program play itself from that starting position, to see what the ending would look like. (I'm such a beginner that I often can't tell why someone resigned!)

I'm using mac osx, but could possibly find some other platform if necessary.

thanks,
Eric

if you're ok with the command line (terminal), then gnugo can be used that way. I'll have to look up my notes on how to do it.

thanks -- I just tried it ('-l fname.sgf') and it generates the next move only. Any suggestions? I'm wondering if there's an xwindows client that would help.

I'm also willing to buy commercial software if necessary.

gnugo -l file.sgf --score aftermath -o out_file.sgf

that's exactly what I wanted -- thanks!!!