I've been working on the Find/Replace panel, which is certainly the biggest feature left for v0.9.
One thing I'm still on the fence about is the search options. Right now there's just one, case sensitivity, and I've got it in there as that "A=a" toggle button. When you press it, it switches to a "down" state, and your search becomes case insensitive. Press it again to toggle back.
I like toggle buttons because they are efficient to use, and you can always see what options are in effect. What I don't like is that they take up a fair bit of room. It's fine if we have just one, but we probably also need "Whole Word", and maybe "Selected Text Only" if you have an extended selection. So that would be two or three toggle buttons, which space away from the Find/Replace fields.
But I might regain that space by removing the "All" button, and having all results checked by default. You can uncheck all (or check all) by holding option while you toggle any checkbox. So by default the replace button would replace all anyway; and if you want to do fewer, you uncheck a few, or option-uncheck one (which unchecks all) and then check just the ones you want. I think this is a good workflow as long as you know the option-check trick; I would need some way to make that easily discoverable.
So, anyway, this is what I'm currently working on... once this is all ironed out, v0.9 will be very close!