Happy to share! Anything someone else takes up is one less thing distracting me from whatever I
should be focusing on.
First, there's Snowdrift.coop. This is my full-time project, and I'm paying another full-time dev (less than he's worth) out of my own pocket, but we're more than happy to welcome contributions from others. An interview with my co-founder was just published in Linux Magazine: http://www.linux-magazine.com/Online/Features/Snowdrift.coop Drop in on IRC if you want to get involved!
I've also got a chore tracking site that I put together for my household, which my wife and I have been finding valuable. It needs some work before I do anything substantially public with it, but I'll share if anyone's interested.
Aside from that, there are a few things I'd like to have or see explored:
I'd like a notification daemon that lets me review recent messages and batch notifications by priority.
I'd like to see a file system (I've been calling it "cronfs") that lets you place filesystem objects in time. Working right, you could implement cron atop this in a couple lines using dnotify to watch a "now" subdirectory. A big advantage of this is that you can trivially do level testing ("should this service be up?") instead of just the edge triggers that cron supports, but I'd also like to see what else would grow out of it.
I'd like to see exploration of "genies" and an implementation of more of them. Genies are a framework (conceptual more than code, so far) for long running individual tasks requiring repeated interaction in the shell. The name is meant to invoke "not quite a daemon" or "a kind of daemon". The idea is that when you invoke a genie it registers with your shell before dropping into the background, future commands can be easily sent to the genies associated with your current shell, associated genies can be polled for updates before rendering the prompt, and the meaning of commands doesn't shift between polls/commands. I have a (hacky) libpurple client implemented this way, as well as associated scripts: https://github.com/dlthomas/genies
Something I think would be worthwhile, but might be sticky politically/socially, is adding a couple new capabilities in terminfo and building out support in screen/tmux and enough terminal emulators to be meaningful. There's two things I would like to see here. The less controversial is a way of signalling "this is a notification, get it to the user appropriately" - which urxvt should send to dmesg, ConnectBot should turn into an Android message, screen/tmux should forward if they're able and just note if they're not, &c. More controversial is a way of rendering graphics within a subset of characters that are then still treated like characters - there have been a few attempts in this area, none has quite worked out. Rich terminals in general - historical and future -are an interesting research topic.
I also have some things I'd like to blog about, but they probably are too personal to hand off, at least in the sense that explaining them in enough detail for someone else to write them would basically be writing them myself.
I may add more as I think of them, but I should go do some cleaning...