ComputerWorld has done some research, and compiled a very interesting list of the PC skills that currently have little or no demand. Here is a very shortened version of that list. Please check the source link for the full version of the list with a much better explanation of, well, everything.

First place: Cobol.
Cobol is a very old programming language that saw a quick spike during the Y2K paranoia. However, since then, Cobol has been slowly on the way out, Universities no longer teach it, and rarely anyone uses it.

Second place: Nonrelational DBMS.
DBMS is an old database protocol, sort of like MySQL. MySQL is in fact one of the database protocols that replaced DBMS.

Third place: Networks without IP addresses.
This one's self explanatory. Back in the late 1980's/early 1990's, corporations thought it would be a sweet idea to put their computers on networks without IP addresses. Considering that a computer's IP address is like a regular mailing address, networks sans IP kinda bit the dust.

4: CC:Mail, the classic store-and-forward E-mail system of the 1980's.

5: ColdFusion, another forgotten programming language.

6: C/C++ programming, which is used by high school programming teachers as a torture device.

7: Powerbuilder, yet another forgotten programming language.

8: Netware engineers, who did stuff with the programming platform Netware. Netware was a great programming platform right until Microsoft unleashed NT. All Netware programmers got certified in and switched over to NT within 2 years.

9: PC Network administrators, who's role is becoming automated by very smart and easy to configure/use Windows servers.

10: OS/2, a joint attempt to make an operating system by IBM and Microsoft. It's been an almost unheard of operating system with a very small group of dedicated users, and was officially discontinued in 2005.