Welcome to Physics Forums, urtalkinstupid and nakayama!
Here at Physics Forums we have a sub-forum devoted exclusively to the exploration of new theories, such as alternatives to Relativity, namely Theory Development. Perhaps a Mentor could move this thread there?
Some of the views expressed on the two sites for which links were provided are relatively common; many folk have difficulty understanding relativity, and are lead by their misunderstanding to try to build alternative theories. IIRC, some university lecturers sometimes give these as homework near the end of their Relativity courses, so students can sharpen their own understanding by seeing how others have gone astray.
In any case, the real test of Relativity isn't gedunken experiments, it's experiments in the lab and out in the universe. AFAIK, both SR and GR have passed all these experimental and observational test. In fact, if you consider tests of QED as also being tests of SR, Relativity has been shown to be consistent with experiment to approx 1 part in 1018.
So a suggestion for those who think they have a good alternative theory: please provide details of an experiment whose results should clearly distinguish between your theory and Relativity.