A little research has made me think that FileMaker is indeed Access for Mac, but perhaps a little more robust. I worked with Access for years, never really liked it, and am glad to be away from it (I always held a grudge for MSFT killing FoxPro, which I did like).
It is hard for me to imagine it as a good solution for a web based app used by offices in four locations around the country, plus many others logging on from home, etc.
Using it does not make much sense when MySQL, SQL Server, etc are available for the data storage and ASP.NET, PHP, Ruby etc are there for the programming.
Mike Thomas