Here are a few cool places to visit online if you're feeling like you're out of ideas :
First of all I wasn't aware that Vangogh did so many watercolors, very interesting to see ...all his works are available here: www.vangoghgallery.com/waterco…
Secondly, what has been inspiring me recently is the amazing control and freedom to the paint given in Asian style painting so here are some Japanese/Chinese techniques for you to check out if you wish to:
Some more ideas for you:
What you could do with your "dead" brushes!
An unusual technique using splatters and blowing air to move the paint:
I hope you like these and get something out of them,