Tartini in Tune

I've been using various tuning apps on my iPhones for a couple of years now.  I think I've had around six or seven, and most of those I've paid for.  They've pretty much all worked, after a fashion, but I've never been all that happy with any of them.  They're usually finicky about the sound level.  They fall over if the tone they pick up is a long way from what you're trying to tune to.  They're just not that visually appealing.
When you start to play a note, the usual process goes something like this: No, can't hear anything.  No, still nothing.  Nope.  (Play louder)  Maybe.... Yes, you're very sharp.  Err no wait, I meant flat.  Play louder, can't hear you again.  Oh, that's perfect!  (When even with my tin ear I can tell the horrible sound I'm making is still clearly a million semitones from being in tune.)
In steps Tartini.  It's iPad (or computer) only at the minute, but what a revelation! It's easily the best quality tuner that I've used - both in terms of picking up a sound, and giving a stable predictable indication of what you're playing.  For that alone it'd be the pick of the crop.  But that's only skimming the surface of what this app will do.  Where it really blows everything else away is that it doesn't just attempt to replicate a hardware guitar or chromatic tuner.  It's like the people behind this have really thought about what you want from a tuner, without any preconceived ideas about what your typical hardware tuners are.
The app opens up, showing you a music staff. (Well, by default it shows a compressed view with around 10 octaves, but it's easy enough to change it back to a standard music staff.)  You play a note, it shows up as a line on the staff.  If it's a little flat or sharp, then the line isn't perfectly centered on the staff.  If you're nowhere near the note that you're trying to tune to, it's very obvious.  Simple, and obvious once you see it, but brilliant to make that jump from the traditional hardware tuners that you've probably used before to something which takes full advantage of the hardware available.
It doesn't just stop there either, as you play notes it will tag them on the staff - including sharps and flats.  Also included is a vibrato monitor, which gives you a visual indicator of whether your vibrato is centred around the note as well as smooth and consistent.
The icing on the cake is that it records all the visuals so you can scroll back through and analyze your performance if you're so inclined.
There's also PC/OSX/Linux versions of the software - see the University of Otago site. (I've not used these much at all, they're not as pretty and it's just far more convenient to use the highly portable iPad for this kind of stuff.)  If you're interested in delving into the details of the software there's source code and papers about it on the site as well.

And it's all free.

I can't complement it enough.  Go and get it, even if you're just a hack of a muso like me.  You'll love it.