Ah, smells. I totally know what you mean. Out here in Arizona, in the spring, the smell of the blooming citrus trees is overpowering. Especially at night...the air is just perfumed with a jasmine-y smell. I'd know that smell anyway.

Also, there is this bar back home that has always smelled a certain smell and whenever I'm there visiting and walk in...time falls away.

More than smells for me, though, is music. I've been a big music nut ever since I was a kid and certain songs/artists/albums can just take me right back to places in time.