With regard to the situation in the UK, the recommended UK guidelines for testing Diagnostic Radiology Equipment (formerly IPEM 77, revised edition report number IPEM 91) have now been published (Jan/Feb 2006) and suggest a concise set of tests to be carried out on a daily/monthly basis and further tests on a 6 to 12 monthly basis. Details of how to obtain this document can be found here: http://www.ipem.ac.uk/ipem_public/article.asp?id=366&did=49&aid=1915&st=&oaid=-1
PACSnet can also be contacted for advice on LCD monitors in particular, as these are currently under evaluation as part of their remit. A contact there is Jonathan Turner, Principal Physicist, 020 8725 2619.
Finally, the IEC are preparing a document on testing monitors for medical purposes (IEC 61223-3-6, Ed 1.0, replaces IEC 61223-2-5), and when this is published, should form the basis of a British Standard on the subject, but I do not have the information to say when that will be available.
As an absolute minimum, then if you can get access to an SMPTE pattern on your monitors (possibly requiring the help of an engineer), then scoring this test pattern is a fairly simple and quick process and should at least identify any gross problems on a day-to-day basis. I can also point you to a presentation I have given on the topic, through the KCARE website: http://www.kcare.co.uk/Education/Online%20presentations/2004/NPL%20Sept%202004%20HC/Digital%20Image%20Display%20in%20Diagnostic%20Radiology.html