The only suggestion that I could think would work would be to place identical tracking codes across all your sites and this would amalgamate all the data from the sites. This could be added in as a second tracking number so you do not lose your current tracking system.
You would then be able to generate one report for the combined data for your sites or you could create filters, one for each site (setting 'Domain'), and apply the filters to different sections of a custom reports.
This would only work for future data and would require some time to set up, however after this point it would streamline the process and allow you to see the data in one place. Depending what data you wished to view you could set up custom advanced segments for each domain, you could view 4 of these simultaneously in the standard reporting interface.