There are people who like Inception, and then there are people who love Inception.
You know who the lovers are: the people staying up into the wee hours of the morning, blogging about their latest and greatest Inception theory. They can tell you twenty-five potential ways to read the ending and give you an exact replica of the plot. They've created some pretty awesome and very helpful sites for those of us who don't want to get an aneurism trying to figure out how all the dream levels work and if the kicks actually make sense.
These wild-eyed Inception-maniacs also create useful infographics and maps. Do not, under any circumstances, tell these people that they have too much time on their hands. That would not be wise. (Have you ever been hit over the head with a keyboard?)
Of course, there are other sorts of fans too. These guys are less concerned about understanding Inception and more concerned about using it as a creative platform. For starters, there's fanfiction (there's always fanfiction) that deals with smoochy Arthur-Ariadne stuff.
Of course there are all sorts of other fan creations, from posters to, umm, more posters.