A Scotch ATG 700 puts down adhesive strips on the back of all your paper/object needs. It may look like a massive pricing gun, but really it's a thing of wonder that lives in one of my adhesive drawers.
That's how the adhesive (think the sticky part of tape) is laid down on your paper. It makes a pretty great bond. While the price of the gun is PRETTY high for a glue toy, the small cost of the massive refills makes up the difference.
I use it mainly for gluing things together, but it can also be used for closing envelopes, wrapping packages, etc.
I tried out the Tombow Mono Adhesive (above) before I used my employee discount to invest in the ATG. It's nice, but the refills cost the same as the dispenser, and you get barely any coverage. (I keep it in my art bag now, so I can glue things into my books.)
**btw- I'm sorry if this entry is a little weirdly written, I'll probably rewrite it later, but I am working on day three of a massive migraine that I think has shorted out my brain a little.