app for putting phone on silent except for some contacts

[rvank]

Is there an app for iphone 3gs that can be used to ignore incomming calls, aka phone is silent, but where calls from selected numbers still can come in as normal.
I want to use this when i sleep so only calls from famely can come tru, i sleep during daytime, work in nightshift.

Thx in advange for your advice.
Rob.