Here is another (what turned out to be) a great craft for a baby/wedding shower. A personalized quilt. I precut 7 inch square quilt patches out of an off white fabric.. enough for each attendee and some extra. Bought a few paint pens and rounded up a slew of colorful permanent markers (thanks Erin!), and made sure people had magazines or plastic table cloths to bare down on because the ink will bleed some.
At the beginning of the shower, we told everyone what the idea was - showed them a sample patch and gave them the entirety of the shower to decorate their personalized quilt patch. Even though the less-artistic were a bit apprehensive, I think everyone was genuinely excited about the end result. I gathered all the pieces and am sewing it together to send to our mommy-to-be before the baby's arrival.
This would work great with messages to an engaged couple and use their wedding colors to finish out the blanket!