The domain of Bitcoin exchange wm-center has been shut down by the government
http://www.businessinsider.com/the-feds-just-seized-another-bitcoin-site-2013-6the onramp to
BTCbitcoin is getting more difficult every day with each shutdown
but are they down for good? Mega upload is back and wm-center claims they will be back
we currently can not serve US-based customers and US citizens. We will resume our services on US market as soon as will finish the process of obtaining required licenses, we expect this will happen in the fall of 2013, and we'll post update here as soon as everything will be ready.
http://usa.wm-center.ru/