Notices

ovi for predownloaded guidance while abroad/out of data coverage (naff interface, crap search, no voice, but reliable).

Modrana for all other scenarios (great UI for driving, espeak voice, guidance, x2 and x4 map zoom, great custom POI & local search, proactive developer).

First, let's define the navigation types:
There is vector maps navigation and raster maps navigation.
Vector maps ("artificial"): for n900 unfortunately we can only have Sygic and very, very sucking OVI (sometimes I even forget it's there).
When it comes to Raster maps - there are plenty of choices, some better some worse but NONE of them will give u a...professional navigation if, for example, you are a taxi driver simply because they all 100% dependent on on-line navigation data even if you have some raster maps preloaded. (Especially frustrating when you travel abroad and have to change sim-cards(((()

So, the answer is simple - if you need a professional and reliable navigation soft on N900 go for Sygic. Preload maps and POI of the location where you are now or will be in future and forget what the words "trouble" and "frustration" are.

i use sygic 10 and rarely have an issue with it, the routing is good and having offline mapping with turn by turn voice guided directions is great. I also have no issues with it in pr1.3, great product wish you got access to all maps for a flat fee though, that is the only downside for me...

Other than sygic i also use geeps, mappero and gloudgps - my favorite out of them would be geeps, all have the disadvantage of needing to be online though which is not a problem most of the time...

http://www.hpsblog.com/2009/07/direc...0-without.html is dead, use this one instead: http://nokiamaps.site666.info

(Use the older maps for 3.0 that the site says work with 3.04 - it is the smaller link, so read the page carefully.)

Sygic Mobile Maps is almost perfect now (as for v8.24). They resolved the issue with German umlauts and "Str." abbreviation when selecting contacts from the address book, as well as the common SIGSEV stability issues both with v8.16.

There is another one I am using since I had my first Ipaq with Linux on it: Navit. I must admit that it is difficult to handle, but I think for offline navigation it is good enough for people like me who don´t need it too often.
When you use maps from openstreetmap you can get the latest ones every day if you like without paying for it.
We made a wiki-page for navit on n900 (sorry it is in german language but experienced users should comprehend the code examples too).
One big advantage of navit is that you can nearly configurate anything, but as I said, it is nothing that works out of the box.

The Question is: how long will the n900 be supported? I guess the commercial support for n900 will run out since Nokia dropped the support too. I prefer an open solution, they simply last longer.
Apart from this, as somebody already wrote: If you need a professional navigation system for your job, get a dedicated one.

CU Michael