uClassify provide a free text classifier service, which you can use by signing up to their API.

The free API allows up to 5000 requests a day, and you can select from their 6 different public classifiers on the uClassify Settings panel.

Please note that each classifier is counted as a separate request from your daily quota, so 100 URLs with 4 classifiers selected will use up 400 of your 5000 daily allocation.