I have consistently watched one LD go by after another for the past few years, and every time I say I’m going to do it, I get distracted and back out. This time, I am going to make an honest attempt, and I’m getting support from my girlfriend this time around (who is going to try to make her own game). Should be very interesting!
I have a bad habit of changing the tools I use in the middle of projects, so I am not going to hold myself to this list… but this is currently what I’m interested in trying out. I don’t want to lock myself into Android development for this, but I definitely want to use this as an opportunity to determine a sweet flow for porting games in the future, so most of my choices reflect that desire. Web-based would also be nice as I’m still astounded by Notch’s success with Minecraft. Regardless though, I do have plenty of plan Bs. 
Hardware: Intel Quad Core I7, 6GB ram, GTX 460 w/ 768MB GDDR5
Platform: Windows (but hopeful for near automatic cross platform support on Linux, Android, and the web as well)
Language: Java
Libraries: libGDX (LWJGL/Slick for gfx backend, box2D for physics), Kryonet for networking (works on Android!)
Tools: Photoshop CS5 and/or Paint.net (2d art), Blender (3d art), sfxr (sound gen), musagi (music), non-stop Pandora (probably tuned to Breaking Benjamin station)
Any other details are too fuzzy to mention, but I think this is a good start… I need to prototype a quick test run in this environment to make sure I don’t waste yet another Ludum Dare.