[FoneWeasel]

Need an app that allows the user to block specified contacts (or all but specified) until 6am the next morning. T-Mobile actually provides this as a service for a small fee (or did).

[CaptainChaos]

You might be able to use iBlacklist, but I am not sure if it has a time function on it.

[capncaptain]

Hey, this app finally exists. Don't Dial (under utilities) - it lets you block your own contacts, or you can have a friend set a password on your phonebook (it expires after awhile).

It's here: iTunes Store

or dontdial.com