So we painted a stripe in the baby's room. Really 3 stripes. Turns out this is pretty dang hard to do on textured walls; there's just no way to get the painters tape flush against the wall everywhere, so you get some seepage that you have to clean up. (Someone has since told me of a little trick with paintable caulk, but it's too late for that on this one.)
BEFORE

To clean up the edges, I've been sitting very close to the wall with a small, flat edged artist's brush to make the line straight. I'm actually pretty proud of how it is turning out, but there's still a lot to do (we're also adding polka dots to the stripe once it is done), so I may very well go blind before we're done.
AFTER