Since sound emulation is such a tricky subject I decided to try a hardware approach. What I did was design a circuit that plugs into your printer port (LPT1 or LPT2). This circuit contains an actual Atari Pokey Sound chip on it (and a couple other chips) to give you real Atari 8-bit sound. The zip file located on the pokey main page contains a schematic, parts list, test program, and programming information (for other emulator authors) on the Pokey printer port sound card.
How well does this sound card work? Well it gives about 98 percent accurate sounds. It should since you are using the actual Atari sound chip to do it. How much does it cost? Well depending on how detailed you want to go (case for it, cabling) it can cost from around $18-$25 US dollars. Keep an eye on this space for some WAV samples of Atari 8-bit programs using the Pokey Emulator and Pokey Sound card.
As of version .61 of Pokey support has been added for the sound card interface. I have been in touch with authors of other Atari 8-bit emulators about supporting the Pokey card in their emulators. So far the ones I have been in touch with are going to look into adding support to their emulators!