And how do you create a shortcut to the khan academy app on yor home screen, anyway? At least on Android, I can think of a not so intuitive way that your average person won't easily stumble upon: 1) google such site/navigate to it directly; 2) then bookmark it on yor browser; and to create a shortcut (app button), 3) tap-hold an empty spot on your home screen; 4) select shortcuts; 5) select bookmarks and 6) finally, select the khan academy bookmark.
Using OpenAppMkt is just like using the regular app market. The only problem, potentially a killer one, is getting your avg user to download it. But here, I hope social recommendations and links just like the one contained in the page above (which take you right to the download page on the respective app marketplaces) will help.