Michael Eskin's sweet suite

Michael is a remarkable polymath, he has the chops not to only get these applications written but also meet Apples' standards review in a single try. His jammer related applications are:

HexJam ($2)- Hexagonal Jammer Concertina for the iPhone or iPod Touch

This app turns your phone into a pocket concertina with 52 notes (3 1/2 octaves) literally under one fingertips.
One can fire up an iTune and jam along with it. Apparently it works really well with 2 iPhones too.
And, to boot it also runs on the iPad. 

HexJam HD ($2) - Hexagonal Jammer Concertina for the iPad

The same thing, but for the iPad. Both of these applications have their own built-in sound.

mJammer ($5) is a Midi controller function for the iPhone or iPod Touch, simulating 1 keyboard per unit.

It links to an Apple or Windows PC (probably Linux too) wirelessly. There are simple instructions for hooking it up. There's no direct sound, but there is an added bonus:this app does have the ability to send controller (volume, expression, modulation, or breath controller) messages by tilting the device with adjustable sensitivity. It also works just ducky running (blown up 2X) on the iPad. With it one should be able to do even better than this remarkable demo of a man with a prototype jammer.

iJammer ($10) is a Midi controller function for the iPad, simulating 2 independent keyboards.
It links to an Apple or Windows PC (probably Linux too) wirelessly. There are simple instructions for hooking it up. There's no direct sound.

This is remarkable; in about five short years, we have gone from where it took Jim Plamondon, a gang of people and a largish fortune to just develop prototypes of jammers, to where it was implemented as a short project by one guy. True, he's working from the large body of background knowledge and work that's accumulated (I modestly point to these two Wikipedia articles: Jammer_keyboard and Wicki-Hayden note layout), and true, this 1.0 version does not have important musical features like velocity. But still ... it does give one pause. 

Limitations: as in all version 1.0 products, there are some little limitations. The basic one is that we didn't get too fancy; Michael delivered what the basic apple application package could easily deliver. This means basically, one finger at a preset velocity per note, and fancy things like a thumb-pad area for the thumb, finger-tip expression control (i.e. vibrato), motion sensing and and ... all sorts of bells and whistles have been left on the workbench. Tough. Better okay and now, than perfect and never. Yet, even at this stage these applications go well beyond the toy.

Shiverware's Musix versatile iPad application

This application is a fully-customizable multiple-layout isomorphic musical keyboard. Each hexagon on the screen is a note, and surrounding hexagons are harmonically related according to the rules you select. The blurb reads:

• Songwriters benefit by discovering new melodies and musical relationships.
  
• Novices find it easy to learn to play.
  
• Experienced musicians are rewarded with an intuitive interface.

If you have an iPad, this looks like a very good way learn music theory.

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