I’m getting a 3d printer soon. What useful things have you printed with yours?
horizontal garden tools holders (shuffle, broom, etc.) in my shack wall,
clippers for opened bags (http://www.thingiverse.com/thing:30664)
but there is many items you can find in thingiverse
Brackets for hanging various things, a eavespout diverter (send water to water plants), among other things.
Tonnes of custom widgets, Learjet cockpit parts and the beginnings of a full size humanoid robot 
It’s truly fun. Cheers
Tons of replacement parts for major appliances, brackets, hooks, feet. Replacements and upgrades to your printer. And TONs of calibration cubes. They may not seem useful, but they are
A Second and Third 3D printer!
Parts for my quadcopter brackets for stepper motors, touthbrush holder all the printed parts for a rep rap Huxley etc,etc makerbeam feet
Covers for encoders on machinery, chess sets, knobs, prototypes for client’s designs, camera and GPS brackets/mounts … spare and upgrade parts for the printer itself !
AR 15 Lower Receiver, animatronics, UAV parts, new 3d printer, ipad/iphone stand, appliance fixes, Toll transponder and GPS mounts for motorcycle handlebars
What are calibration cubes?
A small specifically measured cube to verify that your printer is both symmetrical in the X/Y and Z axis. you print it, and measure it to verify your printer is correctly calibrated.
Whenever any print looks kind of wonky, I print another calibration cube. It helps me tweak filament flow rate, extruder temp for different filament spools. The main purpose is to set/confirm all your settings in your configuration.h file in your firmware. If you Google 3d printer calibration, you’ll find a ton of guides, but I always use
http://reprap.org/wiki/Triffid_Hunter’s_Calibration_Guide
Knobs, in fact I just fixed a “game cam” a camera used to view and track wildlife.
Camera mounts and parts, if you are into photography, some very useful and expensive gear can be printed.
Brackets and mounts.
Screw driver handles (bits are cheap, but the driver handles are typically needlessly large and.cumbersome to handle)
If you have food grade hot ends and filament you can print cookie cutters, and such
Or you could just print custom cookie cutters
@Eric_Moy I personally don’t take such precautions, but I really “should”.
Lamp shades, phone stand, guitar picks, keychain phone stand, glass bed holders, picture hangers, plastic knobs, electronics enclosures, spool holders, guitar string winder, gopro camera mount, printer improvement parts, geocaching enclosure.
Two of 3d printing’s biggest strengths are versatility and utility. It can’t do everything, but it can do many things.