Sew on new buttons!
This vintage-inspired sweater (from Target, a few years ago) had some very pretty pale purple flower buttons, a few popped off and ran away as buttons love to do. Instead of matching the existing buttons, which would have been easy enough, why not switch to some cool vintage shell buttons? And why not choose some brighter colors that coordinate with the pretty yarn embroidery.
From the top: purple, white, yellow, green, blue, brown, magenta and white again. This sweater makes me happy every time I wear it! (and I know - I really should have ironed the sweater first)
Something that doesn't make me happy is something really kind of silly, but...
Yes, I'm a girly girl and I love pink, but aren't there maybe, somewhere out there, some men who might like to learn how to sew a button too! I haven't read this book yet, but it does look pretty good, despite its gender stereotyped cover.
For a manly approach to sewing buttons, check out this video. It is a little corny, but does the job.
Threadbanger also has a great tutorial on How to Sew a Button.
And, in case you were wondering, I do have a few more "button" focused altered clothes to share.