Should We Focus on Vulnerabilities or Threats?

Here’s an interesting question: what is your standard for deciding when to
add a given person to these various services?

1. Twitter

2. Facebook

3. Friendfeed

4. LinkedIn

Here are mine (I think).

Twitter

Anyone that seems interesting. I treat this as a content discovery method in
addition to a personal communication system. I differentiate this by only
doing SMS updates to close friends while using web or app retrieval for
everyone else.

Facebook

Only people I’ve met or know in some way on a personal level–including
people from high school, college, and such. I also include high-profile
people in areas that I follow–but only if I am familiar with their work. The
standard for those types is that I will have something to discuss with them
when I do talk to them. If I don’t, then I don’t add them–even if I know
they’re famous or well-known.

Friendfeed

Same as Twitter.

LinkedIn

This one is like of like Facebook, but for the professional side. In other
words, I mostly add just people I know, and when I add people who are
well-known in my industry I only do so if I know their particular sub-field
and work well enough to carry on a conversation with them easily. If not, I
don’t add all the big names just for the sake of having them there.

What are your criteria for adding to these various services?