A collection of tablet user agent strings. Please add in comments other strings or devices that should be added.
Apple iPad [source]
Mozilla/5.0 (iPad; U; CPU OS 3_2 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Version/4.0.4 Mobile/7B334b Safari/531.21.10
Samsung Galaxy [source]
(Different strings for each model. All devices have a resolution of 600x1024.)
GT-P1000
Mozilla/5.0 (Linux; U; Android 2.2; en-gb; SAMSUNG GT-P1000 Tablet Build/MASTER)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; en-us; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; nl-nl; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; ru-ru; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; nl-nl; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; th-th; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; en-gb; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; fr-fr; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; it-it; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; ar-ae; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Mozilla/5.0 (Linux; U; Android 2.2; en-us; GT-P1000 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
GT-P1000R
Mozilla/5.0 (Linux; U; Android 2.2; en-ca; GT-P1000R Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
GT-P1000M
Mozilla/5.0 (Linux; U; Android 2.2; en-ca; GT-P1000M Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
SGH-T849
Mozilla/5.0 (Linux; U; Android 2.2; en-us; SGH-T849 Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
SHW-M180S
Mozilla/5.0 (Linux; U; Android 2.2; en-us; SHW-M180S Build/FROYO)
AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
Samsung Galaxy S (not a large tablet, not just a phone)
GT-I9000T
Mozilla/5.0 (Linux; U; Android 2.1-update1; es-us; GT-I9000T Build/ECLAIR)
AppleWebKit/530.17 (KHTML, like Gecko) Version/4.0 Mobile Safari/530.17
Windows tablets [source]
In Windows Vista, the user-agent string reported by Internet Explorer includes "Tablet PC 2.0" if, according to GetSystemMetrics(SM_TABLETPC), the device is a Tablet PC.
In Windows XP Tablet PC Edition 2005, the user-agent string includes Tablet PC 1.7. The user-agent string looks something like the following:
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.0.3705; Tablet PC 2.0)