I really like mobiles on cribs. I think they can really complete the look of a nursery. For H-man's room I purchased the mobile that went with his nursery set.
I usually put Harry in his crib while I make a bottle and I turn it on for him. This is his view of the mobile.
Pretty dull, right? Just a whole lotta blue. Harry seems to like looking at it and likes the music it plays (Humpty Dumpty), but I thought it might be getting kind of boring for him. So, I added a little somethin' somethin' to it.
Ta da! Nothing fancy, but I thought a little pop of color would be exciting for Harry. I used my Cricut to cut out the star and then glued little scraps of paper to it. I just used tape to attach the star to the mobile.
If you have a "boring-to-baby" mobile you could really do any number of things to make it more appealing. If you don't have any colored paper you could even use magic markers to draw some squiggles on a piece of printer paper.
Since adding the star to his mobile, Harry has really loved looking at it. He is fascinated by colors and shapes these days!