The nicest addition to my NEX-5 has been one of the many Novoflex adapters, in particular the one to use Contax/Yashica lenses. The Tessar 45/2.8 pancake, silver edition, looks as if it had been designed for the NEX itself. The Sonnar 135/2.8 is long, very long, but falls in the hand beautifully. The Tamron SP 90/2.5 Adaptall is a great lens, supersharp, however not fully optimised for digital, in such in some light conditions and at medium and small apertures, a purple image of the diaphragm is projected in the centre of the sensor.
Overall, I am super-satisfied with the camera. It is the first time I can use my three lenses above with a vertical viewfinder, Rollei-style.