I am a big fan of Houdini 3D package made by great guys at Sidefx.com. I'm watching this software development since version 5 and it's been few years now. Houdini have changed a lot and it finally got cool dynamics two versions back and now, guys at Sidefx are close to releasing version 10. I even own the license of H9 HD which is $99. It has all possibilities of full licensed version but it's for personal use only. If you want to buy full commercial version as it's called Houdini Master, it's going to cost you almost $10k :)

Anyway, Sidefx is close to going Gold with version 10 and you can read some interesting article about it straight from Sidefx office at Sidefx President's Blog 

Most interesting for me is that I've been talking to Sidefx guys about Mac version around 2004 when I worked in Hollywood, but they told me there is no market for MacOS yet, so if some big client will ask them for compiling current Windows/Linux/UNIX version, they will do it. So, after few years they finally did it and starting from version 9, you can use Houdini on you Mac. I've never said that, but hey, Sidefx guys, great job ! Thanks for listening !

Check out these cool fluid simulations made with H10.