One standard for texts and "dead" formulas now is pdf (Adobe).
We can free download Adobe Reader and open documents (in Internet).
Now Elsevier/Knovel is working on same standard for "live" calculation.
In future we can free download ??? and open documents with "live" formulas: input new data for formulas and see new answer!
I think Mathcad (Express) can be this ???. I would like to have some as Mathcad Reader
PS
Now I am working with one team with this ??? - see please http://tools.knovel.com/ie/Help/contributors.htm