For many Mac users, FileMaker has been their database of choice for a long time. After all, Microsoft has never ported their Access database to the Mac, and there haven't been a lot of good alternatives to FileMaker. You could use a spreadsheet for very simple lists, and AppleWorks had a decent simple database, but there really hasn't been a lot of good alternatives to FileMaker for a heavy-duty database. Bento is now available as an easier to use (and more consumer-oriented) alternative to FileMaker. And if you're running a small business, they're probably fine.
But what if you want to use a database with the web? You can use some versions of FileMaker to show your data via the web, and it has some nice tools built-in for that. But what if you're using a hosting site? They probably don't support FileMaker. And what if you're working on your own dynamic web pages (or want to hire someone local to do it)? You need a test database as well as a live one. That means buying another copy of FileMaker to do it right.
There's a lot of dynamic, database drive web sites on the web, and I'll wager not a lot of them are using FileMaker. Many of them are using something expensive like Oracle or Microsoft SQL Server. But a lot of site also use a free alternative – MySQL. MySQL is a free, robust database that you can download and run on many different systems (Macs, Windows, Linux, Unix, etc.). Yes, there are paid versions, with some enterprise features and support, but the free version is probably more than enough for most people and small businesses.
Now, unlike FileMaker, you don't get a nice GUI interface to your data with MySQL – it's all command-line based. But you can download a free program called MySQL Workbench, which will let you control your server and manipulate your data. MySQL comes pre-loaded on OS X Server – all you need to do is turn it on via the Server Manager. Of course, there's some configuration involved – by default MySQL only allows connections from the local machine, for example. Some of the configuration can be done with Apple's tools, but the rest is easier via MySQL Workbench or other tools designed to work with the database.
You can run MySQL even if you don't have OS X Server. MySQL comes with a package installer, so you don't need to know any test commands to get it installed. The MySQL Workbench installs with a drag and drop. You also get a preference pane for starting and stopping your database, and you can set it to auto-start when you start your Mac if you want.
You will most likely have to learn some SQL language to get the most out of your database. But if you are already doing your own dynamic web pages via PHP, you probably understand enough programming to be able to pick up SQL. And if you're using a program like Dreamweaver for writing your web pages, then there are tools that come with it to make pulling your data out much easier, with little to no SQL knowledge.
So if you're a web designer looking to make the jump from static to dynamic pages, or looking for a free alternative to the more expensive Mac databases (and willing to invest a little elbow grease to save some money), you might want to give MySQL a try. I use it for my iScore website that's housing all my baseball data from my 1984 replay. If you check out one of the leagues, you see there's a lot of data in there – and if you go to the "Standings" page, and click on one of the game results, you'll see a page with a link to a "scorecard" for that came. That will bring up a PDF stored in the database – showing you can store just about anything in there (photos and other binary files).
One of my web clients also has a store that uses MySQL to house the data, and I'm looking to convert another client with a couple of stores over from MS SQL databases.
It's also easy to backup and restore your database (you have to have a backup, or Calvin will come looking for you!). It's also easy to take these backups and restore them on another machine (even if it's a different type, like a Windows box). So MySQL databases are very portable.
MySQL has been in use by a lot of folks for many years. Some are worried that since Oracle bought it, they'll do something to kill it off, but there are already a couple of new projects based on MySQL (since the code is all open source), so even if Oracle were to somehow shut down further development, MySQL would live on via one (or more) of these other projects. So I don;t think it's going anywhere any time soon.