Some favourite ideas...
Poems written with syllables that spell out your dog's name, reader unaware (so that the pup's interest is picqued when the right word following another sounds the same as his given monikker).
Beautiful outlaw (belle absente) : A poem which may not include the letters from your loved one's name, for whom it is written.
A novel called X20 (more thoroughly explained here) where cigarette cravings and chapters co-habit.
Now I'm finishing up 'Jealousy' by Alain Robbe-Grillet where the 'absent' narrator occupies every scene without making much of a mark or reference to himself, but watchfully and enviously suspects(and thus notes) that his wife seems to be falling in love with someone else. It's fascinatingly done.
Barriers in the way of writing no longer seem like a wholly negative notion. Perhaps they will eventually encourage the imagination to sprout.