all the time. i gig regularly so to fill in the sound i often play; eg, Em for G. it gives a 6th sound. Bm7 over a G sounds like Gmajor 7th. experiment with your guitar, ioften hit a chord or note by accident to find a nicer sound.
i remember hearing an interview with Mike Rutherford of Genesis talking about the making of We Cant Dance CD, where he says; "as we were jamming to write the music, we never said this is D and that's an F. we didnt realize we were playing different chords until we finished the album." or words to that effect. so i guess the lesson here is: if it sounds right, it is right
Ask not what Chordie can do for you, but what you can do for Chordie.