Scotch tape? Duct tape? What about other types of tape (like the tape they put on supermarket labels?)
I usually try a variety of approaches depending on what the glue is. Most glues seem to be either water or oil based (mostly oil). If the tape is on something that can take some heat, then I might either fill it with hot water from the tap, run hot water against the opposite side, heat it up with a hair dryer or just let it sit in the sun for a few minutes so that the glue will soften. Then I peel off the tape, trying to pick up as much of the glue as I can. I often use the sticky side of the tape to try to pick up any remaining pieces of glue because it seems to come out the cleanest when I don't have to resort to step 2.
Step 2 depends on whether the glue is oil or water based. If it is oil base, either I give it a good rubbing with a light oil like furniture oil, tea tree oil or lavender oil or olive oil. Once the glue is dissolved and removed by this step, I wipe the surface down with a warm soapy cloth. If the glue is water based (usually not gooey or tacky), then just cleaning up with some warm soapy water seems to work best.
Hope this helps.
I've have very good luck with GooGone.
Just a few weeks ago I bought something called "Krud Kutter" from Home Depot. It is amazing! Smells lemony good and cleans anything - especially does well with sticker remnants. Says biodegradable. I have used it on carpet, walls, bamboo wood floors, marble counters... no damage to any of that, but always be sure to test it out on a hidden section before using it.
I also bought something called "Motsenbocker's Lift Off" Stain Removal Kit, which I tried a few times as well and works nice. It has 3 different formulas in a single kit. Good luck!