Ask HN: How do you handle large number of SSL certs?

Currently I have around 120 clients in a multi-tenant application hosted on Windows 2008R2 using IIS7. Of these about 70 of them have SSL certs. Its increasing becoming a nightmare maintaining all of them, so I need a better solution.

My question is, how do these large applications/companies handle managing SSL certs?

I know Windows 2012 and IIS8 supports SNI and maybe that is my answer, but I just want to know if there is a better solution out there from people smarter than me.

Note that switching over to Linux is _not_ an option and we are a Microsoft shop, however if the solution presented requires us to move away from IIS or introduce a layer in front of IIS that is an option.