Good navigation for Europe working on nexus?

I'm guessing you want something with maps pre-loaded on your SD Card so that you don't need an Internet connection? CoPilot, Sygic and Navigon spring to mind, though Navigon seems not to be available for sale from the USA yet. They all cost about the same (ca. 60 euro including maps of Europe).

I tried all three and Navigon is my favorite by far. Sygic is somewhat sluggish and does not conform the android user interface, it does work though - if you can get used to its UI.

CoPilot just always is too late with announcements; it really is not very helpful to be told to "turn right" when you already are at the crossing. Further more it doesn't offer lane-assistance.

Navigon is the best IMHO. It does offer everything you want and provides clear instructions at the right time. The maps are okay (but not as good as TomTom / TeleAtlas) and the lag on my Hero is not too bad.

If you don't need realtime turn-by-turn instructions, look at mapdroyd. The maps are based on openstreetmaps and thus may not be the best in the world but they usually are good enough. And since it's free, you can't beat the price.