yes, thanks. the disc could be printed like this.

Without focusing your angular accuracy will be rather poor I'd have thought.

Also note that this will only give you a compass bearing if you hold the device flat. The appeal of an e-compass is that it works in 3 dimensions.

My preference is for a time and location based overlay of e.g. the sun or moon, which one drags into the right location to set the compass heading. Realistically nothing we do unless you make your own Bluetooth e-compass (or find a gps with one included and Bluetooth comms capabilities) is going to make this day to day usable. Unfortunately.

may be one like a sphere floating in water could improve that, but the shine-through method also need some improvement. I kinda want this for helping augment reality though.

EDIT: I just test with mirror app, black paper with 2 small pin size holes, i think it wont be that poor.

when the compass for n900 will came out......huh....

If you have been following in the thread you would know that the people were talking about having an actual hardware compass for N900.

nokia will never manufacture N900 anymore so I fail to see if nokia or any other companies would be willing to produce a compass for N900.

In other words the last few posts on this thread was heading more of a do-it-yourself solution rather than asking some company to do it.

If you're keen, you can probably hack your N900 to include a digital compass through the ways probably mentioned in this thread or in the hardware hacking section of the wiki page for N900.

Otherwise, there's Columbus which is not a true compass tool but it heavily relies on locking via GPS satellites for navigation.

I've been thinking about this a bit, and i think perhaps you could use audio tones to represent the heading info from a digital compass. Something cheap like a picaxe chip can take the I2C serial data from an electronic compass and convert it to some kind of audio tone. Maybe three tones whose relative amplitude represents the heading. Or maybe even morse or PSK31 to send text to the phone. It would only have to be a 3 digit number Maybe 4, if you wanted higher accuracy.

Then you need software to interpret the audio input, and then serve it to other programs as heading.

Of course you would lose your microphone input, and the speakers wouldn't work while the headphone jack was plugged in, but other than the practicality problems i'm sure it'd work! haha.