I found a blog called Oopsey Daisy, where she does "Mommy School". She puts out theme packs with activities for toddlers and preschoolers. They have a letter, number, color and theme focus. She includes printables too, which is really nice. All for free.
I also found tot school packs - more geared to toddlers and younger preschoolers. Can't remember the site I foundthem on though, and I'm on the wrong computer. I'll find the site.