This is actually a difficult question to answer, given that you did not provide a climate or zone. I know from your member page that you are in the UK, but that doesn't really help answer your question.

A couple options would be Gardenia (Suitable for warm climates) or Clethra (more hardy). Maybe Daphne or lilacs?

~Chills

My sugesstion would be Calycanthus florida'Athens'. Not at all showy but, I would bet that you would have wished that it were planted even closer to an open window!

Mock Orange,if the right fragrant one.Some cultivars are sentless,but the right one smell like haven.Also Budleia davidi,smell good and easy to grow.Calycanthus florida'Athens'lis just as the guy above said it is.Lonicera japonica is a climbing invasive shrub but does smell good in the evening.