Even reading signs as you go places is great for kids, but it would be hard to do that for 15 minutes--outside of NY Times Square, at least. Here are some lists that might help you find books to read with your little--and not so little--one(s).
For age-based ideas for what to read AND tips on how to read to that age group, go to http://www.readaloud.org/bookselections.html.
For several annual lists organized by age group, go here: http://www.readaloudamerica.org/booklist.htm.
The "100 Best Read-Aloud Books" according to a parents and experts from Scholastic: http://www.scholastic.com/100BestReadAloudBooks/.
What are YOUR favorite read-alouds?