Greek small businesses are currently unable to make international payments, and all Greek credit cards are blocked. Therefore if e.g. your hosting bill needs imminent payment, you're in trouble.

Some Greek guys in America have a temporary solution to proxy payments from contributors outside Greece to the suppliers that Greek small business needs to keep them running.

There's a story here: http://money.cnn.com/2015/07/07/technology/greek-crisis-zerofund/index.html

You can submit financial support via prepaid cards https://docs.google.com/forms/d/1UVyiVk6N1haFIPZTkuUrlyo4EbY06rjRT70Aodnw3Bk/viewform

And the link for Greek small businesses to request help is here https://zerofund.org

The people behind it are https://twitter.com/PanosJee and https://twitter.com/jonromero