Exactly what LJAZ says. I use them for everything from hanging the clock on the wall to mounting my storage bay LED lights. I even use them for mounting the alarm clock, fan and table lamp to the flat surfaces in the living room and bedroom (in the 5er) to keep them from moving around while going down the road.
They make an incredibly diverse selection from just the stick parts, "Velcro like" stuff (unbelievably handy) to wire holders (great for holding that table lamp's wire back out of the way) to small, medium and large hooks in various styles and finishes. I even use the 3M Command stuff to mount the toilet paper holder and towel holders in the bathroom. And, yes, they remove cleanly with no damage to everything I've ever used them on. I even use the large hooks to hang "the Christmas stockings with care" in the sticks and bricks. Stick them right to the wall and take them down after the season.
Now, if only I had thought of them...
My 2 cents, your mileage may vary...
2 Cats; J-Lo and Ragamuffin :R
2014 Thor Tuscany 40RX DP
2011 Ram 2500 Longhorn CTD HO
2011 Keystone Cougar 318SAB (now gone)
2008 FunFinder X 210WBS (Sadly gone)