Using Tokyo's SCSK Corp's Curl web language, I have built Curl applets for kanji learning at http://kanji.aule-browser.com
The Kanji by Grade pages now randomize the Kanji, so the first one is effectively a "Kanji-of-the-day" but this also remains the case for the search field's default Kanji character.
In the case of combined grades, the Kanji in the search field always starts as one from the top grade, giving you two "Kanji of the day" - one easy and one more challenging.
Compared to loading and re-loading Adobe Flash or Adobe Reader updates, loading Curl about once a year seems pretty simple.
SCSK Curl was originally MIT Curl and is now in version curl9 known as Curl 8.0
The Curl CAEDE library now can be used to create Android app's as well as web and desktop app's. Apple iOS app's are coming soon. Curl app's already run on Windows, Mac and Linux PC's, laptops, netbooks and ultrabooks.