With the number of e-mail addresses people have, I think that all
business networking sites should allow people to have multiple e-mail
addresses as part of their profile.

LinkedIn does this right.
OpenBC‘s implementation forces you to have
a business e-mail, and changing this requires re-confirmation *and*
locks you out of your account. Yes, you can set your personal e-mail
address, but it's not the same. For example, I'm known as sachac AT
ca.ibm.com and sacha AT sachachua.com . Both are equally valid for
business, and people will look for me using either address. sacha AT
sachachua.com is also my personal e-mail address, as is sachac AT
gmail.com and sacha AT sacha.free.net.ph . LinkedIn allows me to associate all of these e-mail addresses with my profile, ensuring that people find me easily. I can even log in with any of the e-mail addresses. OpenBC doesn't. Waah.