I don't think any website can strengthen your connections with friends; you have to do that yourself. That said, if I wanted to invite a friend over for tea, I can: 1. Email 2. Call his/her cell 3. IM 4. Leave a message on the FB wall.

I don't like to do 2 or 3 because they are real-time or require availability. For me, there's no difference in 1 or 4.