Whoa, when I dug this thread up from the dead I didn't want to start a big argument like what's going on right now. Thank you mikey for all those links for GPS programs. Here is my opinion so far on what I've seen.
GPSNavX 2.16 - This program seems to be more oriented towards boat users. Doesn't really have navigation capabilities, but more "tracking" ability so you can see where you currently are and where you have been.
MacGPS Pro - This software looks promising, but it WAY too complex to use while I'm driving. I'm going on a 3000 mile drive (yes, you read that correctly) and after the first 500 I just want my screen to show the road, information and essential "GPS Navagtion" stuff. All that information is just too much, the maps are too complex and just isn't right for my requirements. This looks like some amazing software for hiking and a co-pilot.
Outdoor Navigator - This is more meant for a PDA and while I do have one of those, it's the wrong one. I'd basically need to buy a new iPaq. At this point I'll just buy a real in car dedicated unit, mount it and be happy.
Garmin Street Pilot 2620 - Perfect. This is EXACTLY what I want. However, it doesn't work on my mac screen and basically defeats the purpose of using my computer in there at all. Especially at the pricy tag of 1600 bucks!
Route 66 - Let's face it. Route 66 is a mapping program that they added GPS capabilities to. It's not driving software per say yet, just what seems to be the best thing to it.
The street pilot stuff is amazing. If the prices were a little more reasonable I think everybody would have one of them in their cars. What I really like are programs like Co-Pilot GPS. It has an arrow on the screen for your next turn, where you are in a little map, speed, altitude and other useful or useless but fun information. With the arrow and distance to turn (and I'm pretty sure speaking ability too) it truly is a driving GPS program.
Now some other programs are even coming out with 3D driving directions with businesses and buildings in 3D on the maps. This might be a little excessive but I'd really like a co-pilot "esque" software solution. I love my mac, but don't tell me the cheapest option (I've said before, I have a GPS unit and I have an old copy of Co-Pilot for PC's) is to go buy an old laptop

. I guess I use this machine for work, I can't expect toys like this all the time.
BEN
PS. Nobody take offense to what I've been saying here, it's my PERSONAL opinion and my PERSONAL needs. I bet a lot of people would agree with what I'm asking for, but to each their own.