Mac OS X is actually quite good at handling fonts if you know where to stick them. In addition to TrueType and PS-fonts, it also handles .ttf fonts (windows).
There's several places where you can put your fonts, depending on where you need them. your user folder/Library/Fonts is perhaps the most appropriate.
As for an ATM-replacement, there's Suitcase 10.1, which as far as I've tried it well worthy, although it's only advantage I can see over Mac OS X built in handling is the ability to turn on and off fonts at will and place them whereever you want...