No hotels in St. Petersburg?

It seems that with white nights (tourist season), and also some major economic forum in St. Petersburg, there are about zero hotels available in St. Petersburg. I've called a dozen already, all full. I called a travel agent and he also said he's having problems getting anybody hotels.

I tried kakdoma.ru, which lists St. Petersburg as an available city, but when I called them, they said they do Moscow only. (I guess they only do St. Petersburg on their website? But their website only returns Moscow search results....)

Any recommendations for an apartment rental website in St. Petersburg?

Update: nura found me some apartment rental. :-)