I'm sure that there are quite a few people in this position, and I just wanted to give you some hope. I used a website that claimed that they had updated summer associate wanted ads, so in desperation I signed up for a trial account. I sent out probably about 30 applications via email to the market that I want to be in and mentioned in the email that I would be in town the next week. From these applications, three firms called me to set up interview times, which were essentially callbacks (same format 5-6 attorneys and lunch). I ended up getting three offers from this.
I will say that this could just be pure luck - I don't think that the website has the most accurate information because it does claim that Thelen is still looking for summer associates, but it did give me the contact information for several firms. Having said that, I would definitely email resumes still because I am still getting responses from firms. The firms that I applied to are primarily satellite offices of V100 firms.
Hope that helps! Good Luck.