Has anyone ever encountered an app that...

[motorious]

Acts like a little black book. Basically what I am looking for is an app that stores certain contacts and communications from those contacts (i.e. text messages, e-mails, call history, etc), in a password protected "black book". I'm finding I have too many kids playing with my phone and want to limit what they can see (at least that is the official explanation)...

If this hasn't been developed, it's a great idea which would probably sell quite well ....