I really think you should, as Wombat was thinking earlier, find a way to stream files to users on the internet, such as hosting an internet radio. That would be neat.
I'm not sure that's something that really belongs in an audio library, but maybe as an extension. I may well look into it.
Also, the WAV support is a little flimsy, like when I'm playing this huge 132 MB WAV file the program locks up for a long period of time until it decides it wants to play. Maybe you could implement a way to stream it from disk instead?
As Paddy says, use BASS_StreamCreateFile, as you would with MP3 or OGG. I guess you were using BASS_SampleLoad?
Another thing, if you possibly could, be able to pull individual samples from module files and either save them to disk or load them into memory, allowing them to be played later as well as being able to play them in any pitch, any volume, appling DirectX effects, etc.
That is something that can already be done by the application (reading the samples from the files), though I'll admit it is a bit complicated
The main principle of BASS is to make anything possible, but to remain concise. The last thing I want is for BASS to become bloated and messy. So nothing gets added without careful consideration, especially things that are already possible for the application to do