I've been messing around with 2-meter packet for a while. When I started (around 1992), there was all kinds of activity on 145.09 around the Denver area, mostly people texting back and forth and leaving mail messages and those ASCII pictures--it was like Facebook! That sort of activity seems to have all but disappeared lately. Now all the noise is on 144.39 with the APRS stuff.
The local ARES emergency organization uses 2-meter packet for the weekly net as well as for trainings and emergencies. It's very helpful for sending lists and other logistics.
I've been using a 1200 baud DRSI DPK-2 TNC (no longer appear to be made)...started off using it with a 80286 PC and now I use it on the laptop with a USB-serial adapter and a modified version of Winlink. The radio is still a Yaesu FT-470. I use it at home as well as in the car or camper--I bring a 8AH gel-cell to power the TNC and radio away from home.
I've played around with APRS a little too. I built a Foxtrak kit and use it with a Garmin eTrex (old serial-style). It works well in a car with a 1/4 wave magnetic mount antenna. I've been trying to use it by bicycle but I think the antenna has been the limiting factor--I haven't made it into the I-gates from the bike. An encapsulated twin-lead J-pole is in the plans.
I also like to bring up APRS with the computer, set the radio to 144.39 and watch the APRS stations show up on the map. I use UI-View 32 for that.
Of course they have all the new radios with packet and APRS built in now and the mobile devices running sound card packet--I'm way behind the times, I suppose.
I've never tried HF packet but that's supposed to be pretty exciting.
Eric