I'd like to embed a spreadsheet into my website so that:

1) The user can edit data and their spreadsheet gets changed but nobody else's does
2) The user can perform basic mathematical calculations
3) The user can reference cells (just as in Excel)

I thought that maybe googledocs could work, but I'm not convinced that 1) would be a possibility. Any thoughts on this OR a javascript/jquery solution would be great (I saw a bunch of JS/Jquery solutions on the web, but nothing as simple as what I needed)

Thanks so much,