Can someone give me a brief rundown on some of the popular online math sites.

So far we have done very little organized "academic" stuff at home. DD6 started 1st grade today and I am starting to feel like it may be time to introduce her to some more challenging things. I am guessing school will not be doing this although it is too soon to know anything yet.

DD has always been more into reading and imaginative play and not math. We did stumble across IXL a year ago and she loved it for a short time. She would randomly pick a topic between K and 4th grade though usually 1st or 2nd and if needed I would explain it and then she did it. At first she requested it frequently but if we were busy and didn't do it for a couple weeks then she would forget about it and stopped asking and I never felt like pushing her.

I have been seeing people mention Aleks and EGPY and dreambox and khan academy as well as some books that sound interesting (life of fred, zaccharo, beastmaster). I would guess that with very little effort she could be up to the 3rd grade level quickly although if gave her an assessment tomorrow, I think she has a smattering of skills from 1-3 grade at least. I also think she would be less likely to do any kind of worksheet or book learning but something online might be fun enough to catch her interest again.

Any suggestions on a place to start?