> Besides position reporting, WX monitoring and
> messaging, what can I do with APRS,
That's about it. It's not really a "fun" mode, but it can be very useful and interesting.
> I use it as a base station and my HT is
> not capable of APRS.
If you pick yourself up a unit like a TinyTracker, any transceiver can be used for APRS. I have a Deluo GPS receiver, a TinyTracker, an Alinco HT and Nicad battery I put in a small (6x8x3) plastic case and have used this setup to track myself on long trips across country. If you're anywhere that has a path to an I-node you will appear on findu.com, where anyone can see where you are on a map. The group that I hang out with uses this system to keep track of each other on long trips, and coordinate HF mobile skeds by putting times and freq's into the message text, which also appears on findu.com. It's a great marriage between the internet and ham radio.