Which summer jobs, if any, are useful for clerkships?

[CuriousClerk]

I imagine that to a certain extent this varies by judge (both in terms of whether it makes a difference and what particular jobs might make that difference), but is there any consensus on what type of summer work could prove useful when it comes to clerkship applications? Is it important to try to intern with a judge? Should you be going out of your way to establish ties in desired markets if you don't have them already? Is 2L biglaw work a plus or minus or is it generally neutral?

I'm especially interested in COA. Thanks.

[Cupidity]

I've heard its very beneficial to have some judicial experience during law school, either as a 1L during the summer, or through a judicial externship during the semester. It's not so much the line on the resume that helps you though, its the networking, because the judge can either hire you based on your work product, or make a call to a friend who will.