I give him a small toy to hold, normally a Little People giraffe he likes to suck on.
When cadan was younger we used my dressing table as a changing unit in my room and he used to love staring at himself in the mirror.
I have also found colby likes looking at posters that have great black/white contrast. I believe you can get some geometric shapes printed in black on white paper specially for holding babies' interest.
Socks on hands are great for self soothing at sleep time too and to stop them pulling the dummy out if they are used to being swaddled.