I've been an electronics geek since the 1960s when my dad taught me to solder when I was six. The solar panel setup I use to charge NiMH batteries is "one of many" depending on whether I am at home (roof panels) or mobile -- car or camping/backpacking/even cycling, if touring long-distance enough. For the latter, a 10-watt rigid solar panel (17.1V charging, 12V nominal) hooked up to a homebrew "Frankenstein Box" (Radio Shack sealed plastic kit box containing voltmeter, 12V 5Ah alarm battery, diodes for polarity reversal protection, fuses, wiring, 2 cigarette-lighter sockets and 2 Adapt-A-Plug sockets (allows 12V to feed almost any device with a jack) works quite well. I use a Maha/PowerEx 9000 charger, the "Rolls Royce" of NiMH AA/AAA battery chargers (digital LED readouts of everything). The solar panel, similar in size and shape to a legal size pad of paper, fits snugly in a day pack right against my back, leaving plenty of room for all else I carry in there (an older Garmin 60Csx, a Canon camera, flashlights/headlamp, walkie-talkies, and an AM/FM/SW radio, great for deep woods reception) and Platypus hydration, jacket, etc. Every one of my devices runs on AA or AAA rechargeable batteries. True, I can't solar charge while riding or hiking like this, but you'll figure it out.
If you are using "less," I suppose you can do it (charge rechargeable NiMH batteries for your gadgets), but I have always liked building my own when it comes to electronics. I know not everybody can do so, but I say all of this to show that it can be done, what I have is a fairly low-tech (though nice) setup, doesn't cost too much, and except for replacing the alarm battery about once every three to six years, will probably last another fifteen after already lasting fifteen years. There are some rather cheesy solar battery chargers out there as ready-made/turnkey solutions, and those probably are disappointing to most consumers. But take heart: once you figure out a way, it is doable, reliable and cheap-cheap-cheap. Even after the initial investment, I'm sure I save serious coin. Remember, the newer, better sorts of NiMH batteries last a good 500 to 1000 recharge cycles. With almost-free solar power, that's pennies per juice-cycle. Compare that to several bux for an 8-pack of alkaline disposables, and you'll realize it's your money you are throwing away.
Find a good solar solution to charge the batteries for your devices. I don't know what a good commercial ready-made one is, having built one myself, but shop, look, read reviews, build what you have to, get a quality DC or DC/AC charger, spend a bit of money on better NiMH batteries (guaranteed, and at least 2500 mAh for AA, 900 for AAA) and "be free" (of battery tyranny).
(Back on topic). Thanks for pointing out that the Edge family of Garmin devices uses a built-in Lithium pack. Boo: I probably won't be buying one for that reason alone. But thanks to all for the lively buzz about the device. It is exciting Garmin is using OSM for its basemap data in at least one device -- and for bicyclists, too!