Confessions of a Homeschooler - phenomenal letter of the week curriculum FOR FREE, with loads of printables, games and resources. Created by a fellow homeschool mom.
1 +1+1=1 has lots of preschool packs (little lapbooks) ideas and is home to the Raising Rockstars curriculum (you do need to pay for a membership for some of these resources but most of free). Also home of the Tot School link ups. She has a great list of recommended tot educational toys.
Delightful Learning - has a great series on their B4FIAR experiences, love her ideas!!
The Perpetual Preschool - organized by themes, offers, songs, science, snacks, games, crafts and misc. categories
Step-by-Step Preschool - arranged by theme, offers crafts, snacks, songs, book recommendations and links to other websites as well for each theme
Preschool by Stormie - has LOTS of themes, a little disorganized once you get into the themes but some of the ideas are fabulous!
DLTK Teach - this site goes beyond preschool but falls into the same category as the others so I'm putting it here for now.