The RCA RP5022B Digital Voice Recorder is an inexpensive ($31 in the USA) and widely available portable device. It captures 8000 Hz mono audio, compresses it at 700 (Standard Play) or 4000 (High Quality) bytes per second, and saves it to a 64 MB non-removable internal flash memory. When connected to a USB port, it behaves like a USB flash drive, so no special software is needed to copy the recorded files.
Playing them is another matter. These files are not WAV, MP3, OGG, or any other standard format. Despite the .VOC extension, they are not Creative Labs Sound Files. RCA-VOC is an undocumented proprietary format starting with the signature "VCP162_VOC_File", not "Creative Voice File".
On March 28, 2008, I finally solved this format and released a free C program "devoc.c" to convert VOC files into uncompressed 16-bit WAV. Click here for a Windows executable. If you've installed Sound eXchange, "devoc -p *.voc" will play directly to the speakers. If you want your favorite audio software to support RCA-VOC, send the authors a link to this page. Here are some sample recordings they can use for testing.
Aria Stewart has set up an online VOC-to-MP3 converter based on devoc.
By understanding how my code works, it might be possible to write a WAV-to-VOC encoder and use the RCA-DVR as an inexpensive iPod.
Of course, all of the above can be done with audio cables, but analog copying is slow, labor-intensive, and degrades the sound quality.