Junior Finance/Info System Major with no Internship

Hello,
I am a junior finance and Information System major with no internship this summer. I lost track of time my junior semester is couldn't land an internship this semester and only have 3 semesters (year and a half) left of college. As most of you know, getting an internship is a key role in landing a good career for business majors. Many of my friends start there internship soon with great companies and I am left wondering how I can efficiently spend my summer. I just applied to a lot of leftover internships in hope that one would offer me a position. At this point, I doubt that there is much options left for me. What is the best thing to do that puts me in my best position for the following semester so that companies don't think I took the summer off to do nothing? I can try to ask my former boss at a start-up I interned for last year and see if he has a position he can offer me but I don't know how likely he would say yes and I doubt its going to be related to my major. I am currently living in the DC Maryland Virginia area.