I would agree with Tobberoth and expand on it a little bit.
I think it's better to use the keywords as just a key to help you write the Kanji. You really need to expand on each kanji's "keyword" definition and add other meanings, usages, nuance. Becoming married to the keywords, which I think this manner of review just strongly reinforces them, will keep. What I personally liked to do was use an anki deck that tested keyword -> Kanji (writing) ability, then on the answer card had lists of all the common words that kanji was used in (and their English translations). This gives you a very broad sense of usage for each kanji. Nowadays, when I look at a Kanji and am trying to recall its meaning, I usually come up with a list of associated words rather than just one single keyword. And since your writing ability eventually passes from even relying on the keywords to be able to write it (and just pure recollection / motor memory), the keywords usefulness is rather short lived. Eventually the kanji becomes much less a "keyword" and just a kind of general feeling/idea/concept.
Not only that, but Heisig also mentions that reviewing in this manner (Kanji -> Keyword) isn't so useful as this information is generally gained automatically through normal review (Keyword -> Kanji). While reviewing like this
might speed up your recognition ability a bit, I think your time would be better spent reviewing how to write them. Also, I would be worried about spending a lot of my review time typing answers in English.
I do like what bodhisamaya said though... it is pretty useful to remember compounds like that. But I think you gain the ability to do that without going kanji -> keyword.
I think Tobberoth was just trying to be nice and save someone tens/hundreds of hours of review time on a method he doesn't see as very useful. If I posted a method where I suggested learning vast amounts of Japanese using romaji before learning anything about written Japanese, I would be scathingly criticized.

I think it's a similar situation (criticism of what he sees as a failed methodology), though his comments weren't even scathing - just a little blunt.
To the original poster - the app is pretty cool, though.

I like how it brings up the wrong kanji in red if you make a mistake and confuse the keywords for two kanji. You should also give the answer button a shortcut key and keep the focus on the text box, to keep people from having to click in the text box, type an answer, click "Answer," then click back in the text box.
Edited: 2009-03-01, 8:23 pm