I used to use Trader Joe's citrus shampoo. It smelled slightly of grapefruit in the shower (which I liked), and of nothing much by the time my hair was dry. Unfortunately it seems to have been discontinued, or else my local store isn't ordering it any longer.

Currently I use Shikai Color Reflect shampoo -- the one I have at the moment (for darker shades) smells like grape-flavored stuff, but not (to me) heavily so. Their basic conditioner doesn't have a strong smell to me.

I don't get allergic reactions to scents, but I dislike most heavy ones. I should start carrying some kind of neutral soap, because I can almost never use the stuff in a public restroom. I use lots of hot water and scrub, but I doubt it's as sanitary. If I ever run a business with a restroom, I shall put up a big sign saying that the soap has no perfumes and no triclosan (and make sure that is so).