Yeah, looks like VoodooHDA is the issue. I've seen other posts about this causing occasional panics, but also the need to remove AppleHDA from /S/L/E to prevent Voodoo KP. (if I recall correctly, might have got that wrong).
I guess there's no OS version showing since it's too early in the boot - you've got the kernel # there, and i386 etc, so probably nothing to worry about.
To remove /Extra: First, in below, substitute your internal HD name for the generic "Macintosh HD". I'll use that as placeholder and to show how to handle spaces in name.
Note that you can use tab in terminal to complete the entry, so actually you don't usually need to type full commands/file names etc, just hit tab. So you wouldn't necessarily need to manually type "\ "to handle spaces.
Boot the installer (I mean run that, not use USB to try to fully boot the internal HD).
code: cd /Volumes/Macintosh\ HD/
code: ls -l
> This is so you can see the root directory contents in a list, to be sure you are in the right place. Should see Extra, as well as a bunch of other stuff.
code: rm -r Extra
> No need for sudo, as you are running in super-user mode in this version of the Terminal, which you'll "know" by the bash prompt on left of screen ending in #.
Try reinstall Extra as you described above. In even that you still get KP, try to boot internal HD using safe option (-x) at Chameleon, which will prevent attempted loading of kexts that are not needed for a "safe boot". Failing that, try -s single user!!
In any case, if you think you'd messed up your internal HD /S/L/E contents, you could copy the std kexts over when booted to installer. Of course, that might not "just work", since I guess your installer is 10.6.0 DVD, so some differences to what you have as you'd upgraded to 10.6.1.
I think (but again, may be wrong) that the critical kexts that are in /S/L/E which are totally linked to OS version are luckily the same on 10.6.0 and 10.6.1; these are sandbox.kext and system.kext both of which "match" to the 10.6.0 kernel, which also I think was not changed when going from 10.6.0 to 10.6.1. So you are probably safe. But if you'd gone to 10.6.2. then you'd not want to overwrite these two kexts from install DVDs S/L/E onto your HD's /S/L/E. (mentioning this really in case others read it who did upgrade). If you did want/need to copy the kexts:
code: cp -r /System/Library/Extensions/kextnamehere.kext /Volumes/Macintosh\ HD/System/Library/Extensions/kextnamehere.kext
>kext is effectively a directory, so you need the -r flag to the copy command.