How to identify unknown devices on network?

[joe at actionline.com]

How can I identify the unknown devices (????? below)
on my local network?

Source IP:  Devices:	Mac addr:
192.168.0.1 Motorola 	00:24:37:85:73:f0 REPLACED
192.168.0.2 X5003191	2c:44:fd:67:34:ab Ethernet 3
192.168.0.3 Unknown ??	88:87:17:c0:a4:45 ?????
192.168.0.4 Galaxy phn	0c-71-5d-29-dc-ff
192.168.0.5 Tivo 84600 	00:11:d9:55:72:ca
192.168.0.6 Xoom tab 	98-4b-4a-c0-6f-3a
192.168.0.7 Chromecast 	d0:e7:82:c4:5c:ac
192.168.0.8 ??????????	00:19:9d:56:50:2e ?????
192.168.0.9 Nexus7 tab 	ac:22:0b:44:da:95
192.168.0.10 HP laptop	e0:06:e6:a2:93:a5
192.168.0.91 Lenovo  	70:71:bc:3e:00:ed
192.168.0.64 T43 laptop	00:12:f0:34:5c:33
192.168.0.104 BRW008092CAC78E - 00:80:92:ca:c7:8e ?????