On my US trip I purchased a Mio Digiwalker C320 GPS. Its a windows CE 5.0 unit with 1GB of internal memory and SDHC card slot which can take upto 32GB of SDHC card(FAT32).
When buying, there were a lots of units under consideration. The Garmin Nuvi, the Navman 2100T and some other handhelds. However Mio c320 won because
1. Low price (99$)
2. Easy Unlocking, this means this has become a PDA! I can play music/videos/excel/PDF reader etc., etc., and run any GPS software I want
3. Large 4.3" screen
Now its been almost a month since I have been using this, and I am extremely happy with it. My total cost came to
1. 99$ for the unit all inclusive taxes and shipping
2. 13.5$ for 8GB SDHC ( I kick myself for not buying a 16GB card
3. 16$ for Glisson MMCX active antenna with mount
4. 40$ for Oziexplorer CE, the current software I use
The Unit:
Details about this unit and technical specifications can be found on many websites, including the manufacturer website
here. This unit is small, light and has a pretty robust touch screen sensitive to finger touch. Its no iphone, but as touch screen Windows CE devices go, this is pretty nice. For Audio you have a 2.5mm jack, which means for fitting standard headphones you need an adaptor which costs 50rs in the market. If your car has an aux in on the HU, load the SDHC card with songs, fire up the media player and you are good to go.
Another + point is that the unit snugly fits into the travel kit pouch airlines give for free. So I have a protective case from Cathay Pacific to go with it

The mods and hacks:
My first stop was gpspassion.com forums, where I downloaded the Miopocket unlock. I am currently on the version number 39, and its working like a dream. I have tried out various software on this device like Gosmore/Osmtracker/NoniGPS/Beeline GPS Trial etc., etc., and finally settled in on the Oziexplorer CE
The Review
Part 1 : USA with Miomap v3.3
This simply blew me away. Excellent navigation, intuitive controls and brilliant interface. Well interface was not actually Brilliant, I used a skin from a bloke called Jerry. This "unlocks" some buttons and hidden features in miomap v3.3. The unit automatically recalculates routes very quickly if you miss turns, and gives you option of shortest/fastes/most economical route.
What I woudn't give to buy a India.fbl map for this device! Unfortunately satguide sells the younger brother of this unit(mio c230) with Destinator software, which I am told is pretty horrendous compared to Miomap V3.3
Infact in my online discussions I got to know that I was lucky to get this unit with V3.3 as this is the IGO based Miomap. The newer units(Mio Moov series) have Navman software which is not even half as good.
The only downside I found in my usage was frequent signal lost in San Francisco Downtown area due to flyovers and tunnels. Once I left the car parked in basement for few hours, and the gps ephemeris data expired. Due to low signal I had a tough time getting a fix after that. If you are out in open and lose signal in tunnel, its not a problem. You regain signal immediately, however if you park without signal for a day or so, you got to get a cold fix again, which is painful if you are surrounded by trees and buildings. There are few solutions to this problem. Mobile phone users can download the ephernesis data from internet, this is called A-GPS, some Sirf Chipsets have something called instafix, where they download data for a week or so in advance. When fix is aquired and new data becomes available, it is updated.
With neither of this available to me, I targetted the root of the problem, and got myself an active MMCX antenna. The result was strong signal and 2 minute cold fix time, and no loosing signal under flyovers. As long as some sky is visible I have signal!
So all in all it was a delightful experience, and I actually went to Nooks and cranies of San Francisco without worrying about anything. I missed a lot of turns hurtling down 30 degree + inclines, and this unit handled everything.
And the best part, it recognized google kml waypoints. So before my trip I would choose some 4-5 POIs save them as kml in the POI folder, and just enjoy!
So if any of you want an in car GPS for the USA, look no further, this is the best!
Part 2 : India Usage:
GPS industry in India is still in its infancy. So you have lousy software and maps. Basically you pay 2000-3000rs or even more to get a substandard unit with substandard softaware. For example the Mio c230 which costs 65$ in the US costs 300$ here, and that too with not so good maps and not so good software.
So I had two options. Go for destinator from satguide and pay 2000rs, or go freeloader way. I went the latter. Spend 40$ on oziexplorer, and am currently using Google maps or Openstreetmap maps for my navigation. The software rocks, and will navigate me in city or offroad without any trouble. Its fast, neat, little complex to use, but I am getting the hang of it.
I would love to get India maps for Miomap v3.3 if possible. Other options I have is Garmin Mobile XT in the commercial land.