As promised in my post a couple weeks ago regarding raising bilingual kids, I've put together a list of resources and ideas as to how to introduce Spanish to children. 

First, see my "Introducing Kids to Spanish" List in the navigation bar.... it has comments for each item.  Listening to a proper (non-gringo) accent is equally as important as the quality of the actual content and all three CDs feature native speakers.  Of the CDs, I found all but the Cedarmont Kids at a local library, but they are available from Amazon at reasonable prices as well.  Cedarmont Kids titles are available at many Christian book stores. 

Also on the list are a couple of board books we like - we are still in the board book phase of life, but I will be adding preschool books shortly.  I try to find books that are originally published in Spanish by Spanish-speakers for the cultural contribution and not just the Spanish version of American favorites such as Curious George, etc.

Second, you could join or start a Spanish-speaking playgroup (or an "activity group" if your kids are older), as I plan to do next year.  I'm going to ask a native speaker to do the actual talking during the activity time, but I can help with the organizing and planning details.