Phone number data (database of phone numbers and email addresses)

Just a general question about if it is legal to create a database of phone numbers addresses and email addresses from sources like yahoo, the phone book etc, and display it on the web or even charge for exports of this data. Also, do you have to ask permission to link to another site or sub-pages of that site.

You can link as you wish as long as you are not trying to mislead or appear to be one site that is another etc.--and it generally is not a problem to collect public data and assemble it. You should let people opt out if they wish.