As Grimm said, if you can get past the supernatural trappings of Buddhism, it makes sense as a philosophical system.
If you take the supersitious parts out, most of what I've seen in Buddhism seems to be expressed in secular humanism.
Why call it Buddhism if Buddhism includes the supernatural parts? Without the supernatural, as GodlessHeathen pointed out, Buddhism is just secular humanism.
Because, while it's close, it's not.
Secular Humanism (the philosophy to which I do my best to adhere) doesn't address attachment or compassion in the same philosophical bent Bhuddism does - it addresses, instead,
value. What it does, as a philosophy, is attempts to show how human life and endeavor has value for the simple sake of its humanity, and how
humanity has value and should be prized for its existence, and lauded when it's at its best. It reduces interaction to a sort of value judgement, and - well, frankly - that may be its genius.
It's very easy to be ethical and moral as a secular humanist because any individual interaction can be 'reduced' to the idea of 'which selection a) causes the least harm and b) offers a marked improvement to the lives around me?' There's a huge philosophical underpinning there, but like Sagan's "concept of the number one", it's not important to practice.
Bhuddism and the Ninefold Path, on the other hand, focuses (philosophically) on the underpinning itself. To a bhuddist, coming to understand the 'why' is infinitely more important than the thing itself; the goal is to have the practitioner come to understand the idea so intimitely that the value judgement happens somewhere in the reptile brain, before conscious thought. You do the right thing easily, and without effort.
It's the difference between a guy working a heavy bag in the gym, and someone practicing something like escrima or karate'. The martial artist learns body mechanics, practices until every move becomes instinct; the guy taking a self defense class learns the techniques, but still has to consciously apply them.
That isn't to say bhuddism is 'better', only that secular humanism has a different focus, and has truly endeavored to shed all of the trappings of 'spirituality' that aren't important. Compare, if you will, Krav Maga to Shaolin-type Kung-fu. The former is a distillation, a methodology, just as effective without any need for a discussion of 'energy' or 'chi'. Kung-fu is no less effective, but has lots of trappings that make it... well.. 'spiritual'.
In the cafeteria of philosophical concepts, though, Humanism owes a lot to Bhuddism, Taoism and (oddly) Christianity. It establishes value and builds on the premise of these older ideas, approaching methodology through the fundamental concept of people being important without the necessity of God or god-thought.
Anyway. I can prattle on for hours - but there
are two bhuddisms: philosophical and religious.