I am not in university yet (six more weeks and I will be!) so I cannot really comment on the popularity of posters of uni students, but I've found for those my age, the most comment poster is of a scantily-clad female spread across the hood of the car (for males) or (and I shudder to write this) Justin Bieber (for the females). Most people I know have not even heard of Oscar Wilde.
As for myself, most of my wall is covered. I have a section of wall dedicated to black and white images including Brando, a smoking Cobain, Ava Gardener (the fox!), some hand-developed photos I took of the local cemetery, the infamous 'Kiss' poster (that every young lesbian needs on her wall of course), some blurry pinhole photos and an image of New York City. I have a collage of photos of friends and family that forms the shape of a heart on another wall. Another wall has some abstract paintings of mine, a branch from my favourite childhood tree that was cut down recently, an artwork from the 2010 Sydney Art Biennale, a record, a poster my friend and i had to do for a Children Services class (depicting families with different cultures and utilising every racist and stereotypical view ever made of every race imaginable- particularly each of the ones we belong to) and a large map of Sydney and suburbs circa the late 80s.
Another wall is covered by record covers.