Lately I've been trying to avoid sites like dribbble as much as I can. And started looking into old art books and modern industrial design magazines and blogs.
I've found myself going for long walk around the city more lately when i come across creative blocks rather than looking around dribbble. Looking up every once in a while and engaging in conversations totally unrelated to design can go a long way.
Outside. Pictures. Things that are living. Sometimes I find myself staring at http://stuckincustoms.smugmug.com/ for hours.
I love http://vi.sualize.us/
I paste magazine clippings or photos in a moleskin and use that as a "real" inspiration journal, and organize any inspiration I find online on my pinterest boards (@emmielouise) or via dropmark. Although I primary work with the web medium, my inspiration stems from all sources - I particularly turn to interior design for color inspiration as well as overall feel.
This was interesting on Lifehack.org recently about finding inspiration from unexpected successes:
I also love finding inspiration from old things. Things people have forgotten and take for granted today. I think Aaron Draplin does a great job of keeping his eyes open for "old" stuff. Which inspires him on projects like Field Notes. I've got a blog post about finding inspiration from things people obsess about that highlights some of what Aaron's done and has a video of what he collects.
Hearing Aaron talk about design always gets me excited. His obsession is super interesting and inspiring.
For me the keys to design are cross-pollination, observation and curiosity. Inspiration comes from becoming very good at keeping several problems on the back of my mind, and actively being aware that anything I'm looking at, whether I'm walking down the street, using an everyday object, watching a movie, etc, etc, could be the solution to one of those problems. In this manner, I don't look for inspirational materials, inspiration comes to me.
I am always searching for interesting, minimal blogs. Quite hard. Land Book (http://land-book.com) is also a nice site to get inspired.