I want to comment on the grammaticality of:
•*I request you to do something.
Something hotly debated by tchrist, FumbleFingers, RegDwight and others above.
I agree with tchrist, this is not an acceptable grammatical form.
The reason for this, I think, is because request is not a catenative verb, i.e., it can't be followed with an infinitive (even separated by the pronoun "you") unless it is in the passive form. So while RegDwight above is correct in saying that
"The letter requested him to report to London immediately."
is correct, it would not be correct to say:
"The letter requests you to report to London immediately".
The first iteration (from OED) is only correct because request appears in a passive construction.
As reference, I provide: http://en.wiktionary.org/wiki/Appendix:English_catenative_verbs
I see this incorrect use of request constantly working as a legal editor at a major Japanese law firm (e.g., "We request you to sign the document immediately") - invariably, I change it to "We ask you" (since to ask is catenative) or "We request that you sign the document immediately".