I have downloaded a couple of free Gerber Viewer and none seem to be ideal. GerbMagic has a few nice features, but it is not free (I guess I could spring for $130), but it is very crude in a lot of ways.
I have used GCPreview before (quite a while back) and it is still free, but it does not have an easy way to measure things and some other things are a little clunky. Maybe I have gotten used to the odd interface of Eagle... But it is nice in that it saves all the layers and drill info in one format.
Others that I have tried in the past were pretty poor and often were only demos. Are there any good, free gerber viewer programs I should know about?