Are you familiar with Echolink and IRLP? They are two networks that combine ham radio repeaters and the internet to allow you to link repeaters anywhere in the world and talk through them using only a hand-held. Just find a repeater (or node or reflector) near you to use as an entryway and then look up repeaters you might like to connect to.
IRLP:
http://www.irlp.net/
Echolink:
http://www.echolink.org/
Another fun thing you can do with a hand-held is listen for and work through amateur satellites. If your HT is a single-bander, you can still track and listen to them.
Check out this article:
http://www.k6ria.net/PDF/satbr5.pdf
The world of APRS (Automatic Packet Reporting System) is also open to you with a hand-held radio. It's similar to the Spot trackers expedition-folk use, except it transmits location and other data over the radio (and then into the internet).
Here's an interactive map for APRS. If you input your location, you can see the activity near you. You can even use this interface to "get on the air".
http://aprs.fi
You can also put your own location beacon on the system. You can make some cables to connect the radio to your computer sound card or build or buy a tracker. They also have APRS smart phone apps. I put together the Fox-Trak kit ($20) from Fox-Delta (it appears the are currently out of stock) but there are other options. With the tracker, a hand-held radio and the GPS of your choice, you have a roving position tracker.
Do you like community service? Hams with radios are always sought-after for help with special events and emergencies. Your local radio club (or the internet search engine of your choice) can help you connect with the right individuals/organizations. If you're interested in emergency communications, search for your local ARES (Amateur Radio Emergency Services) chapter or start here:
http://www.arrl.org/ares
Mountain-topping is a fun activity and is possible with a hand-held radio. Organized, mountain-top events are held in some areas, or you can just go up on a weekend (when there are more people on the air) and set up your own station. Call out on the 146.52 simplex frequency and if others are listening, most like to make contact with special events/mountain top stations.
One of my favorite parts of ham radio is field operation. You can certainly field-operate with a 2-meter hand held but the lower frequency, HF bands open up a lot more possibilities. Any HF radio can theoretically be used in the field but the smaller, lighter 12-volt ones are better-suited. QRP (low output power) is perfect as the radios are small, simple and light and the power supply requirement is meager (less battery to lug).
Radios designed for field use include:
Yaesu FT-817
http://www.yaesu.com/indexVS.cfm?cm...2B25B12AB4DC9C0D27&DivisionID=65&isArchived=0
TenTec Argonaut
http://www.tentec.com/products/Argonaut-VI-QRP-1%2d10-Watt-Transceiver.html
Elecraft
http://www.elecraft.com/
...and others. You can even build your own QRP radio in an Altoids tin!
http://www.al7fs.us/AL7FS2.html
I mostly use a Yaesu FT-840 for HF. It's a value-oriented rig that does everything well: portable, base station, QRP, and conventional 100W output. They're not made any more but can be found used.
Hope that helps. It's a great, multi-faceted hobby. There's something for everyone.
Eric