No, we’re not discussing old music here (not right now at least), but a great way to find new music. IRCAM’s fabulous database BRAHMS (which surely stands for something…) has recently gotten a facelift, but has luckily retained its incredibly useful functionality.
With a rudimentary knowledge of French (or google translate) you can use the œuvres par genre search to find repertoire for precisely the instrumentation you need. While the database can’t claim to be exhaustive, it does seem to contain some information not to be found elsewhere. The works pages also often contain links to the Contemporary Music Portal, where you can hear excerpts of unpublished concert recordings.