I've use the Scotch brand Quick Dry liquid glue. It takes about 3 minutes to dry, but it does dry clear and holds really well.
If it somewhere it won't be seen, I like the Art Accentz (red backed double stick tape) best, but have used glue dots when out of the better stuff.
Oh, and I've also used just good old fashion scotch tape when it is on something in the back, where it won't be seen or touch photos. Also helps with fraying.