there is no 64bit version of skype available. However, you can use 32bit applications in Debian AMD64.
1) chrooted 32bit sandbox (prefered way)
2) use ia32 libs from /emul/ia32-linux
The second solution is very fast. Install packages:
Download 32bit static version of skype 1.4 or 2.0beta and check if you have all required libraries.
ldd skype | grep -i not
If you have all libraries than you can run skype. It runs flawlessly.