The only thing I'm aware of, which I've used fairly extensively, is Modern Path. It's no longer supported, but there's an SRD for the 2.0 version. Personally, I liked 1.0 better, but there's no online SRD for that.
The game's not exactly the same as D20 Modern; it uses a lot of Modern's OGC, but allows some different combinations that are more like profession classes than D20 Modern's ability score based classes. It's nowhere near as well balanced as Pathfinder.
It should be noted that many of the archetype abilities would be easily converted to Feats and ported over for use with Pathfinder's rules. You could then modify PF classes slightly and just use PF with some additional Feats to represent modern stuff, rather than implementing the entirety of Modern Path.