Have a look at
http://www.prolitteris.ch
I can't find the documents in English but here's the French version:
http://www.prolitteris.ch/imaf/pdff/bildf.pdf You find the internet rates on page 44.
For commercial websites you should ask at least 45 CHF basic right PER MONTH, 60 CHF per photo if more than one is used. If more than 100,000 hits are achieved, you can add 10% but I don't know how you can verify this.
Because they didn't ask prior permission for the reproduction of your picture you can add 100% of the above mentioned sums.
Because they didn't mention your name you can add another 100%.
So basically for this one picture you should ask 135 euro PER MONTH. I don't know how long it's been online, however.
PS: I've asked for compensation twice. I was paid once and I'm still waiting for the settlement in the second case.