I use the free Inconsolata font (by Raph Levien) to program and as shell font, and I like it a lot. I have seen this blog post: "Adding straight single and double quotes to Inconsolata", that offers Inconsolata-dz:
http://nodnod.net/2009/feb/12/adding-straight-single-and-double-quotes-inconsola/

So I've uses FontForge to modify more his Inconsolata version, to fix some of the things I don't like of Inconsolata. This is the result, my Inconsolata-g:

Here you can download the font (ask if you want a ttf version too):
http://www.fantascienza.net/leonardo/ar/inconsolatag/inconsolata-g_font.zip

My changes:
- Single and double quotes ' and " are now straight, this comes from Inconsolata-dz.
- , . ' are a bit more visible/thick, because such symbols are really important in C-like languages, and you need to see them well. (Now the comma of , is a bit bigger than the comma of ; but I don't care of such useless symmetries, I use this font for practical purposes).
- The ^ is a bit wider, because it's used often enough in C-like languages, as bitwise operator, and it deserves to be more visible.
- The curved upper leg of the lower case r is a bit more visible, it was a bit too much thin before. This is a small change.
- In the latest version of Inconsolata the zero digit is slashed, this is quite positive and helps tell it apart from upper case O. But if you have many zeros in a row 00000000 such slashes produce a "vibrating grating" for the eye, that I don't like. So I've replaced the slash with a small point. I use such font is large enough size, so the point is very little. If you use such Inconsolata-g as a very small font such tiny point becomes almost invisible. This is the first time I use FontForge and I don't know yet how to add size hints to fonts.
- Numbers are a bit larger (keeping the font non proportional), so I can read them a bit better. This has the disadvantage that zero is now almost as wide as uppercase O, so the little point of the zero is important.
- The symbol minus - is a bit lower, so it's a bit better aligned when I use a smile :-), this has the disadvantage that the horizontal lines of - and + aren't fully aligned any more.
- [] are now about as tall as () and {}, so Python collection literals have a more uniform look.
- In future I may make the upper side of ! flat and make the lower case t more straight, but in practical situations this doesn't bother me, so I have left them as they are for now.
- The font is bigger than Inconsolata, this comes from the Inconsolata-dz, I don't like this, but it doesn't bother me much, so I've not changed it.

There's another important thing I'd like to change: to keep the bold chars of Inconsolata-g as wide as the non bold versions, because I'd like to keep them non proportional when a computer programming editor shows keywords as bold. I don't know yet how to do this with FontForge (I accept suggestions).