How do you store your exported JPEGs in Lightroom?

I shoot in high res JPEG and usually after a trip or a shoot of my baby, I tweak the pictures I like and then export them in low res JPEGs for Facebook or other online albums. Over time, I have sub-folders called "low res jpegs" within each picture folder to store these lower res pictures. These folders, obviously, are not imported into Lightroom otherwise there will be duplicates. This system works but feels clumsy. Just want to see what other Lightroom users do out there.