harlequins will work, but only in a small school
You could get 10 neons and a honey gourami.
Tiger barbs are too active for a 10 gallon, and I believe cherry barbs would work, but only one or two.
If I was you, I would do the pygmy cory and micro rasbora set-up, as mentioned earlier.
My personal favorite stocking is a pair of rhinogobius wui with 5 white cloud mountain minnows. Keep in mind that a set-up like that is coldwater, and white clouds might be illegal in your area.