2dBarcodes

Standards

QR-Codes

massively used by japanese people, most asian phones natively support capturing codes using the camera.

Datamatrix

adaptation of QR-Codes as a ISO standard, which is now public domain. semacode uses datamatrix for linking to websites.

Shotcode

Circular codes used for marketing.

Readers Software

ActivePrint Glass for Nokia series 60 phones, can read datamatrix & qr-codes. (not tested)

Kaywa Reader (free) for many phones, can read datamatrix & qr-codes.

References

Matrix Codes & Visual Code Recognition on Cellphones