Let users indicate their skills in their profile, search based on skills

I think this is a great idea!

I suggest having a role signup, with autoassign role, let have a different role like "company" "freelancer" "student" with different fields, location, skills, so the user search can be with different field with taxonomy profile etc. I am waiting for commons 3 officiel release so i can make this addition.

One of the issues we've had with different role signups is that some fields may be required that don't apply to all roles, but are really needed for one or more. Then you're stuck with making fields the roles don't apply to required. There's not an easy way to provide links to different registration paths either (AFAIK) because that would be a lot more usable.

For example: Say you have a directory site with members and companies who want to sell stuff. It would be better to have a register page for members and a different one for companies. Or in education, a school may want different information from a parent than a student or from a teacher than a student. In our case, we require teachers to enter a school id in order to login, but not a school administrator because the school admin may have multiple schools that they are responsible for in a district.