The "Atari ROM Checker" aims to analyze and identify Atari 8-bit operating system ROMs based on their size and checksums. It contains a database of all known shipped or prototypes of Atari operating system ROMs. It is open-source, written in pure Java, and runs fine on Windows, Linux, and Mac OS X. The download and documentation, including the complete list of detected ROMs, are available here. The sources are available here.
The download also contains a simple automatic ROM dumper in Atari BASIC that runs on all Atari 8-bit machines with BASIC. Just boot the "AtariROMDumper.atr" with BASIC enabled. It will create a 16k file, "D1:OS.ROM", and an 8k file, "D1:BASIC.ROM", which you can analyze then.
In addition, the included "AtariROMPatcher.atr" disk image can be used to display, compute and fix OS ROM checksums of Atari XL computers. It also includes the option to replace the built-in floating-point ROM with any 2k replacement ROM you have available.
Feedback can be posted in the AtariAge (English) thread.