So far all I can come up with is milk chocolate and chocolate milk.
“House cat” and “cat house.”
“Library school” and “school library”.
“Police state” and “State Police.”
“jumper cable” and (sometimes) “cable jumper”
“Piano player” and “player piano.”
“Whale sperm” and “sperm whale”
board game and game board
cable TV and TV cable
recording studio and studio recording
teapot and pot tea (maybe that doesn’t count since teapot is one word)
Cheese head and head cheese (unless Cheesehead is also one word)
(if the above two count, then) bookcase and casebook
Soda Club (a brand name of the syrups for those home soft drink makers) and club soda
box lunch and lunch box
I can probably come up with more later.
“queen size” and “size queen.” 
good one
“off-hand” and “hand-off”
Butthead and head butt
Also a good one.
Can’t believe I was stumped after one example. Guy at work was selling candy bars for his son’s school and I read milk chocolate backwards. Tried to come up with other examples and was like ‘Fuck it. I’ll ask the SDMB when I get home.’
black eye and eye black
Fish (or meat, or whatever) market
and
Market fish (what the sales manager for Birdseye does).
You use a sheep pen to pen sheep (and a cattle prod to prod cattle).
If we’re choosing a color, I’d give the green light to light green.
Batman.
Man-bat.
House boat and boat house
Which show dog won the dog show?