I was mentioning it because there may be people interested in a web version of the poker calculators. As far as I know the known names (pokerstove etc) are all Windows-based and only Ed Miller has an online equity calculator in his page.

There may be more poker players like me who doesn't use Windows at home and I could see the value of having a re-sized small web window while playing with just three boxes (pot, my stack, opponent's stack) plus a small pre-selection of opponents ranges (ex: top 10%, top 40%, any two) so it can be used in real time.

I don't think that's true at all. It depends on how much use you really can drive. With an online app, with no app install, and purely organic growth and a whole ton of community evangelism, I could see it be a really successful web app.

Aren't online gambling sites some of the biggest spenders on online ad sales? With revenue of $6+ billion per year, I think a good chunk of that must go to lead generation.

Poker players are pretty used to installing GUIs, so I don't think web-based would help. Every poker client is a GUI (and for good reason), as is Poker Tracker, Poker Stove, SNGWizard, etc.

I don't know if you're doing ICM calcs or what, but anything beyond a simple odds calculator should be a native app.