For Spelling we have enjoyed:
This is a sister site to Mathletics which we occasionally use with our math lessons (under Mathematics).
We've enjoyed Study Ladder and it has certainly improved over time. Obviously it covers more than just literacy, so, again I could have this slotted into many categories, but you get the idea. I've re-subscribed this year to see if it helps tamāhine 2 in particular.
The huge advantage to Study Ladder is that it's one fee for everyone - unlike Spellodrome which is per child. These figures all add up and as much as I don't stop myself from subscribing to great resources, I do have to keep such things in mind when weighing up whether to re-subscribe or not.
The following websites we use on occasion. There's so much choice on the web, but these are a few we've used to compliment our schooling.
For my friends in the US and Canada, I came across these lovely CM copywork series:
This next site is free membership, with some free copywork available, I've printed out the Vincent Van Gogh copywork. :)