i made myself one. bought a variable adapter and a usb extension calbe. cut the cable and spliced the wires to the adapter. now i've got a variable voltage usb power supply that connects to the mains.
i connected the other end of the left over usb cable to some small cpu cooking fans whick i put behind my laptop to keep it cool. that way i can vary the speed of the fans vs the noise level.
LOL, got a Zen Mosaic?
My bro got one from a promo in the newspaper i think you know, and I tried my iPod adapter: didn't work.
My dad's BlackBerry has an adapter too: didn't work.
I think it only wants to charge when connected with a PC.
If you're not in a hurry to get one keep an eye on Creative's Online Store. They throw special offers all the time, so if you don't mind waiting a bit you might be able to get a cheap official charger direct from them. I got a really good deal on a remote and an accessory pack on that site a couple of years ago.
Egonny: Creative sometimes set their players up so they only work with official Creative chargers. I remember this was an issue with the Zen Micro; the player would still charge with a 3rd party adapter, but slower than usual and the lights wouldn't pulse. It wouldn't surprise me if they're pulling the same dirty trick again.
If it won't charge with anything but the official adapter, it might be a resistor running along the unused 5th pin of a miniUSB port if it uses one to charge... I know some phone companies do that to make you buy their accessories.