000-299 ~Computing, Phil, Psych, Religions
300-329 ~Social Sciences, Politics
340-369 ~Law, Social Work, Criminology
400-599 ~Languages, Natural Sciences
600-649 ~Medicine, Engineering, Agriculture
650-699 ~Accounting, Management
790-799 ~Performing Arts. Film and Recreation
900-999 ~Geography, Travel, History
A820-Z829 ~Australasian and Junior Fiction
You can set an alert so that Google searches the web on a regular topic gathering hits on a topic of interest from a range of sources (including news sources, videos and blogs).
You can run a number of alerts concurrently, and revisit your Google Alerts account to modify/add/remove alerts.
For advanced Google searching tips, look towards the Advanced Google searching guide.
Book Reviews can help identify books in a subject, published recently which could be worthwhile reading.
Ideas for finding book reviews
Other databases may offer similar features or try finding Book Reviews on the Web from reputable sources.