The on-line "journal," The Medieval Review, is a quite-possibly useful stop for research. Here is how the web site describes its history and purpose:

Since 1993, The Medieval Review (TMR; formerly the Bryn Mawr Medieval Review) has been publishing reviews of current work in all areas of Medieval Studies, a field it interprets as broadly as possible. The electronic medium allows for very rapid publication of reviews, and provides a computer searchable archive of past reviews, both of which are of great utility to scholars and students around the world.

TMR operates as a moderated distribution list. Subscribers receive reviews as e-mail; TMR posts each review as soon as the editors have received and edited it. There is no paper TMR. Once posted, reviews are archived and available for viewing, searching, printing, etc. on this website (http://www.hti.umich.edu/t/tmr).

As this blurb indicates, the site casts a wide net; all titles pertaining to medieval studies are represented, so reviews devoted Aquinas are few (however, they can be very good). Being entirely database-run, the web site allows one to run a search on a term in a title, in the full-text of the review, the reviewer’s name, and the publication author’s name. The results are listed, and individuals can be read on-line, and the complete citation information is provided (including the now-important persistent URL reference). You can gather together reviews into a "bookbag" (akin to a shopping cart on a commercial web site), and, when you’re done searching, you can have the results displayed, e-mailed to you, or you can download them in a format ready for import into a standard bibliography program. As always, one’s search strategy has to be carefully honed; simply plugging in ‘aquinas’ or ‘thomist*’ in the search field for a book’s title would let slip by a careful review of Kevin Flannery’s book, Acts amid Precepts (Washington, DC: CUA Press, 2001).

Another option for you—one I am diffident about—is to subscribe to a listserv feed from the site, where every new review will be sent out to you. That could be opening the fire hose!