37Signals Chalk is the first that comes to mind. But we're doing a few of these apps where I work, and my HTML5 and CSS3 book shows how to do an offline app wit

37Signals Chalk is the first that comes to mind. But we're doing a few of these apps where I work, and my HTML5 and CSS3 book shows how to do an offline app with the Web SQL storage API too. This is actually really cool stuff when you think about applications for business. You're not gonna write games with it, but you can make usable interfaces for your apps. And if you feel the need to be on the app store, grab Titanium, use the Titanium.UI.webview control and point it at your mobile site. We're proably going to do that to make a few of our web apps show up on the stores, because we don't have the resources to develop native Android / IOS versions of the apps we are building. So we'll do Rails apps with HTML5 / CSS3 / JS and jQTouch or jQuery Mobile, and wrap them if people demand appstore access.