Briosafreak
Lived Through the Heat Death
The world's newest and most advanced 3-D animation software teamed up with the first true next-generation video game.
Unlike other free game modification utilities, the XSI EXP for Half-Life 2 gives full access to all the professional features available in SOFTIMAGE|XSI. Everything you need to create Half-Life 2 characters, models, and environment elements is here. You can design characters, mix and blend animations, render interactively or use real-time shaders, and then export your models to Half-Life 2. Download it now!
Yep here's the first HL2 tools for the modders out there. Good luck.
http://www.softimage.com/products/EXP/HL2/