OMG, an M-WAVE card!
I had one of those installed in a PC once. Those things are nuts!
It’s a telephony audio card. Designed to add all sorts of telephone audio features, like answering machine (voicemail) stuff via your PC, as well as I think being a sound card, modem, perhaps other things. My boss/friend thought it was really cool, and I got to be guinea pig to try it out and figure out how it could be used. It was kinda amusing, but was also kinda ape, as I recall, doing weird funky stuff. Fairly amusing, though. It would answer the phone, and do things you wouldn’t generally expect a sound card or a modem to do with the same device. I remember there were certain reliability issues with the software, and that it was a lot of fun to make fun of. You got to say M-WAVE a lot!
As for how much it would be worth… I don’t know – try to find a sale of it on eBay or Amazon or some such place. It’s a collector’s relic or wacky hacker’s toy, but I doubt anyone’s got a great demand for them. I could be wrong… even I have a certain sentimental fondness towards them, but they were wacky.