"Something that work" or "something that works"?

Googling both sentences I find many references with or without -s. Should I add the -s to the verb after "that"? Is it considered a third person singular?

I'm searching for a rule to apply to the verb after "that".

Another example could be this:

people that work (56,100,000 hits)
people that works (710,000 hits)

In English Grammar (ISBN 0-06-467109-7), something is listed in the indefinite pronouns always used as singular, together with somebody, someone, each, either, everybody, anyone, etc.

The correct phrase is something that works.

Googling both sentences i find a lot of references with or without -s.

I didn't expect to find this, but you are right:

"something that work"     159,000 hits
"something that works" 38,500,000  hits

This is the weakness of Googling, that wrong stuff, if repeated often enough, starts to look legitimate. The correct one is "something that works".

Is it considered as third person singular?

A verb after "something" should be in the third person singular form, yes.

3rd person singular verb should match the 3rd person singular noun.

• He/she/it works.
• He/she/it who/which/that works.