Are there any standard tests to measure psychopathy? While looking into another question on how to measure the adoption of norms, I came to wonder whether there are any standard tests to measure psychopathy.

What are the accepted standard tests to measure psychopathy?
The Hare Psychopathology Checklist is considered the current gold standard for measuring potential psychopathy. If you're interested in psychopathology, the book Without Conscience by Robert Hare, Ph.D., is a fascinating read. He has a second book called Snakes In Suits, which I have not yet read, so I cannot recommend or not recommend it. Dr. Hare has a website with a lot of fascinating information and links about psychopathy.

Anyhow, the Hare Psychopathology Checklist is abbreviated as the PCL. There is the regular PCL (First Edition), the PCL-SV (Screening Version), the PCL-R (Second Edition - Revised - Adults), and the PCL-YV (Youth Version). Only a clinical professional specifically trained in administration of the PCL or PCL-R can give an accurate assessment and interpret the results. When I was working with offenders, I sent exactly three individuals to have a PCL-R assessment and all three times the offender came back as having exceptionally high psychopathy scores. When you work with offenders you learn what the psychopathy vibe feels like.

The primary purpose of the PCL, any version, is to determine if psychopathy is present. There is no perfect test to predict recidivism in any population; there are simply risk factors that, when combined together, demonstrate a lesser or higher presumption of risk for recidivism, and risk is dynamic (see below). If I may quote from the Colorado Department of Safety, Division of Criminal Justice, Sex Offender Management Board, as I did in my answer regarding pedophilia, I think this sums up recidivism in psychopaths quite nicely: 


Risk is dynamic. Treatment and supervision systems must be flexible enough to impose greater external interventions during periods of high risk and reduce interventions as offenders internalize and demonstrate risk management skills.
The presence of certain character or personality disorders is a risk factor for sexual re-offense. Mental health science has no identified cure for personality disorders. As a result, long-term treatment and supervision may benefit adult sex offenders with
personality or character disorders to maintain changes and refrain from sexual re-offense.
Prediction of the risk of re-offense for sex offenders is in the early stages of development. Therefore, it is difficult to predict the likelihood of re-offense or future victim selection. 


John Pick listed the Levenson Self-Report Psychopathy Scale in his answer.

When working with offenders, we administered a self-answered test called the ASUS, which addresses risk factors. As well, we administered the Level of Supervision Inventory (LSI) which also looks for risk factors in offenders on community supervision (I'm being vague here because both the ASUS and the LSI are copyrighted material). 

There are hundreds of articles on psychopathy and a variety of topics. The website HALO works with law enforcement in topics in forensic psychology, including psychopathology.