Deviant Art is an artist community for many types of art. It is a large and very open community of artists and has a lot of inspirational work. It also has a lot of amateur work so you may need to dig if you are looking for something cutting edge. Deviant art is also an excellent resource for fonts, patterns, brushes, psd templates and much more.
Show and tell for designers. Essentially this is almost a competition and a place to showcase work, it’s also an exclusive community where members must be invited, this is also why you can find some great modern work here to inspire you.
Behance.net is an online portfolio website with beautiful designs from professionals (as in they get paid well) designers. Now there is no limitation to who can have an account but it is clear that much of the content is curated. If you want your work to be seen this is a great place to be featured. Also if you are just looking for inspiration this is the place to be inspired. The work is very nouveau, modern and of the highest quality.