I'm a native app developer so had a few devices (iOS and Android) used already for testing that started off our Device lab.
I also purchased outright a Blackberry (pre webkit) a Samsung Bada(dolphin browser) phone and Windows Mobile 6 (both Opera Mini+mobile and IE) phone. We've also had a few donations of older phones.
I suspect that most developers test on their own devices as they go, and thats a (relatively) modern smartphone. The more edge cases the lab can represent the more worth it has for local developers.
I have a look through game and electronic exchange shops for older & obscure devices to get my hands on for the test library. We ask for donations either of devices or cash to purchase missing devices and look for either main stream non-webkit or non-touch screen phones. Apart from phones we'd also like to get hold of a Nintendo DS (or similar) for testing.
Are there any other devices that should be on the lookout for that aren't phones or tablets? I know Clearleft have a smart TV as part of their lab.
Thanks
John