These have recently come down in price from $14.99. Shame they're not universal but they're still polished, well thought out apps.
iPhone: http://itunes.apple.com/au/app/the-elements-for-iphone-4/id3…
iPad: http://itunes.apple.com/au/app/elements-visual-exploration/i…
Note: They also come in a UK/Ireland version which I think only differ in spelling.
Also, I contacted the developer to see if the iPad version is going to be supporting the new iPad soon. They responded saying: "We will soon be releasing an update with a number of significant enhancements, including optimisation for the retina display. This will be a free update for all existing owners."
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