What Language was used?

There is software that we use at work and I'm curious what language they used to write it. Are there any telltale signs for major languages that would indicate what the program was written in.

There is another program we use that I can tell was written in VB6 or before because of their "About" dialog. They didnt bother to change any of the variables to reflect their program...

I don't think there is a way to find the exact language a program was written in. However, since you mention the style of the About dialog maybe you could check what languages were around during the last year mention in the about dialog, then see any images much that of your program.