Amongst all the other things I studied in college, I took a few courses in typography and was actually the layout editor where I worked on campus.
As a result, I have an unhealthy obsession with readability/legibility.
When I read a book (or MS), some things just stick out at me so much it drives me nuts. It's not my fault, I've been trained to notice. I'm sure the majority of people don't consciously note these seemingly "minor" typography issues.
One of my biggest pet peeves? Two spaces after sentences. (Please note that I am entirely aware that this is still an acceptable typing practice, as horrifying as it is for ease of reading. I do not condemn you for your vile two-space habit if you have it.)
But, so you know, you don't need two spaces after your sentences. Here's why:
Modern computer typefaces allow proper distance between a period and the next sentence! They program it in, guys, promise.
See, back in the good ol' days when people used typewriters there was only one choice in font: courier. (GAG!!! [can you tell I have opinions on this yet?]) And on those pesky typewriters, each letter (and space) was allotted the exact same amount of room. That meant the "i" had the same space as "m" and "W." So you'd get all these awful ugly gaps of serious grossness.
Since everything was given the same space on said typewriter, you HAD to give two spaces between sentences so everything wouldn't run together in a terrible mess. Once a manuscript was all typed out like that, a typesetter would then set type in a totally different font (thank goodness) and put in the proper spacing between sentences. Then printing would ensue.
Well, word processing has come a long way since then. Now our programs give "i" a small amount of space and "m" enough room to groove. And guess what? They even put the right amount of room between sentences without you having to press that space bar twice. So give your poor thumb a rest and tap it once...if you can. (I know, I know, habits are hard to break. At least now you know it's a BAD, BAD habit;P)