Flyboy - when we lived next to a farm and had flies in the summer, we used to gather large bunches of mint, lavender and any strong smelling herb. Bruise the leaves and hang up in the kitchen near the window. Flies don't like this and although will not rid them completely, it makes the kitchen smell lovely!

Yes, as Floramay says, anything strongly aromatic will do the job. Lemon verbena (Aloysia citrodora) and Lemon balm (Melissa officinalis) are particularly effective.

There's also the so-called shoo-fly plant, Nicandra physaloides.