One thing that has been an improvement around here in our laundry scene was the addition of personalized lingerie bags.
I purchased one bag for each child from a big box store for $1 each. Each child has their own bag with their initial across the top (thanks to a permanent marker). This hangs in their closet (clipped to a hanger; one bag of clips from the big box store was a few dollars). They add their dirty socks and underwear to their own bag.
Monday and Thursday are "bag days" for laundry. The kids bring their bags and throw them in the washer. I put the bags through a normal wash cycle, dry them in the dryer and the kids pick them up in the afternoon. Then, they can match the socks (or not!) and return them to their drawers and fold (or not!) their unders and return them to their drawers, then rehang their bag to collect more dirties.
This has been great because:
1) I don't spend time matching and sorting socks and underwear. (SPEED)
2) I don't have little socks and underwear floating through every load of laundry- I know they will be done twice/week. (Mind-clearing)
3) They are responsible for their own things (which is the grand idea, anyway- right?). If they haven't been putting their items in their bag or if they don't bring their bag to the laundry, they won't have clean things to wear. (Character development)