Right handed. And having recently had my left arm in a cast for 74 days, I am eternally grateful.
Mostly righty, but lefty when things seem not to come to hand easily.
I’m right-handed, but my left is dominant for a few things. I drive more with my left, snap my fingers on the left, and some other things. I mouse with either hand (I have a mouse on each side of the keyboard).
Also, my left eye is dominant.
I am predominantly right handed, but I throw with my left, and hold a guitar and rifle left-handedly. Not that I can play guitar or own a rifle.
My left hand might as well be slightly deflated latex balloon, it is that useless. When I dislocated my right elbow a couple of years ago I was completely helpless for about a week, I couldn’t do anything. Then, even with the extreme pain and limited movement, my right arm was about a million times more capable of doing anything than my left.
It’s sad really. I have tried so hard to condition my left hand to be at least semi-useful, but i always get frustrated and give up because it never gets any better.
I’m left-handed, but like the OP, if a tool is designed to be used right-handed, that’s what I do. I taught myself to write with my right hand when I broke my left hand in high school.
I figured out that I can also throw darts (but not a baseball) right-handed. A dart throw is different from throwing a ball. I found that my natural throwing motion interfered with my dart throwing, so I applied proper dart-throwing technique to my right arm and it works.
Oh, I forgot about that. I throw darts with my right hand too. The people who taught me how were all right handed, and I wasn’t doing any better with my left, so…
I’m mixed up, but I blame elementary school. 
Until first grade, I wrote equally well with both hands. School decided it wasn’t ok, gave me some test (I do not remember this), and I ended up writing left-handed. I bat left, but shoot pool right. Scissors and knives, right, eat left. So yes, it depends on what I’m doing as to which hand I’ll use.
My handwriting with my right hand looks like first grade, still.
I’m fully right-handed, but my dad was rather mixed. I’m fairly sure he wrote left-handed, definitely played golf lefty, and probably batted and threw lefty as well. But I believe he played racquetball right handed, along with other random things. Been a long time since he’s been around though, so that’s about all i can remember 
If it helps, I am exactly like this as well.
It’s very frustrating…I occasionally have a small handedness identity crisis and try to transition activities to my left hand…then get frustrated and revert to this strange pseudoambidexterity.
I’m comfortable doing most things with either hand; my right hand tends to be dominant, except when it comes to the “two handed” bat / golf club sort of thing. I feel way more comfortable in a “left handed” stance, but because I threw right handed when I started playing softball, my coaches forced me to hit as a right handed batter, so I tend to still default to that for both softball and driving a golf ball. I prefer to putt left handed though.
My feet tend do be more lefty though. I skateboard/surf/snowboard goofy footed (basically a left-handed stance), which is more typical of lefties. My left foot is my jumping/hopping foot. When I play soccer, I can play pretty much equally well with both feet. I do have a bit of a more natural kick with my right foot, but I actually think this is because I’m much more comfortable with my left foot planted. I just don’t really feel comfortable balancing on my right foot for some reason.
I write and eat left handed but when I drink and play sports, I use my right hand. I can use a computer mouse both ways and often switch to avoid sore wrists.
I write and eat and drink with my left hand. I am right-handed when it comes to anything sports-related. I tend to use the computer mouse with my right-hand, but can manage just fine with my left if I need to.
I consider myself to be left-handed, although other lefties make fun of me because I wear my watch on my left hand, as well.
Left handed: write, golf, baseball, bowl,
Right handed: scissors, shoot gun, soccer, mouse, skateboard
Ambi: tennis, shoot pool
I describe myself as left-handed, because i write and throw left-handed, but i’m really all over the place:
Left:
Writing
Throwing
Bowling
Kicking (soccer, etc.)
Shooting (rifle or shotgun)
Scissors
Chef’s knives (cutting food for cooking, etc.)
Knife and Fork
Some tools (saw)
Wanking
Right:
Tennis (and other racket sports)
Golf, Baseball, Cricket and other “bat” type hitting.
Computer mouse
Spoon (for cereal, ice cream etc.)
Knife (spreading butter, jam, etc.)
Some tools (drill, screwdriver, socket wrench, hammer)
Shooting (handgun; never fired one, but it would be with my right hand)
Whoops. I voted by accident; I don’t actually have anything special about my hands.
I do everything right handed except masturbate which I only do left handed.
I’m sure that could potentially be interesting to a psychiatrist I guess. 
I have this problem, too. I write left-handed but mouse right-handed, which sucks for Photoshop work. I finally bought a graphics pad so I can use the pen in my left hand when I have really fine editing to do.
I’m about as mixed up as mhendo is. For example, I do needlework left-handed but knit and crochet right-handed. I play racquet sports right-handed but fence left-handed.
I am surprised the first two options are nearly dead even.
I’m totally right-handed these days. Once upon a time I could do most things with my left hand too, but then my wrist was broken and still doesn’t work properly any more. That means that my left arm is the one I always use to carry stuff and it’s noticeably more muscular than my right arm.