Best free educational websites I've used, so far:
I haven't been online much with my kids lately (I mean it's summer after all!), but these are the keepers I've used so far:
http://www.timeforkids.com/around-the-world (world culture; people/places),
http://artpad.art.com/artpad/painter/ (painting online),
http://www.dickblick.com/lesson-plans/ (art projects),
http://kids.nationalgeographic.com/kids/animals/ (facts, sounds, and videos of animals),
http://www.montereybayaquarium.org/ has podcasts from the aquarium and activities,
http://news.discovery.com/ (current science and history facts)
or for lesson plans: http://www.discoveryeducation.com/search/page/k-5/science/-/-/index.cfm,
http://www.sfskids.org/ (from the San Fransisco Symphony, fun learning about music),
http://virtualology.com/ (awesome online library for science, art, & history),
and of course http://pbskids.org/ (for educational games).
My son also loved http://readingeggs.com/, and it really taught him to read in a very short time! But it's not free after the two week trial and once it got more difficult he wasn't playing it so much, so we didn't continue it. I recommend taking advantage of the free trial though! And there is a free app for your smartphone you can get.
If you're a homeschooling family in Santa Cruz county, join us on Facebook at http://www.facebook.com/groups/HomeCruzers/ for park days, hikes, field trips, friends, support, mom's night out, and more!
Also, these sites were recommended by some of my homeschooling mom friends and I can't wait to try them out with my kids:
What are your favorite educational sites?