As you all may have deduced from the recurring font/typography posts here, I'm a bit of a fan. But to this point I've been mostly a consumer of type. I do want to contribute and give back to the community. And I see some pretty big holes that need to be filled.
Helvetica Small Caps
It amazes me that the most popular typeface of all time does not have a small-caps variant. This seems like such a no-brainer to me, and something that would be fairly straightforward to do. I even started it myself, but as I am just learning the tools, it was pretty slow going. I think I ended up doing 2 or 3 characters. And while we're at it, you could do an Arial Small Caps as well.
Tahoma and Lucida Grande Italic
These are UI system fonts for Windows and Mac respectively, and with both are well designed fonts with a bold option, neither have italic versions. And while we're at it...
Helvetica and Verdana true italic
Yes, both of these fonts have "italic" versions, but they are simply mathematically slanted versions of the regular font, aka "oblique". Ugly, and not fitting fonts of this popularity.
Maybe someday I'll get around to doing these projects, but in the meantime, I'm throwing these ideas out there in case any budding (or even experienced) typographers might want to take up the task.