Sanddrag, I own a Samsung BlackJack II.
It's a bit older, but it's been a real workhorse for me.
I use Garmin Mobile XT on it - personally I think it's the best mobile phone GPS app out there. It's inexpensive, is a one-time cost, and works just as well as any automobile GPS out there. I love it to bits.
Beyond that, I primarily text, e-mail, manage contacts, take notes, take photos and movies, browse, and of course make phone calls on it.
I use One-Note to jot down important information, and it syncs with my laptop nicely.
I manage my contacts through Outlook, which also integrates nicely.
It's possible to tether to my laptop via USB, but I don't really ever do that. No 3rd party apps required, you can do it right from Windows Mobile under Internet Sharing.
But beyond that I don't keep a lot of 3rd party apps on it. With a newer phone with a big screen, you may want to install CorePlayer on it. It's a nice media player that's kind of like VLC for your phone.
Honestly, I tried Opera Mini, Opera Mobile AND Skyfire, and I ended up just sticking with IE as my mobile browser.
I have a 4gig miniSD, and it houses GPS maps for a good chunk of Canada and the US in and around Toronto. Once you get a good collection of contacts, texts, e-mails, attachments, calendar items, etc... the rest of the space gets filled up with photos and movies I record every so often.
When I first got it, I tried to load every possible "cool" app I could find, but the more I did that, the more I realized I just needed the core apps, and to spend my time to use them well.
