The most pressing one is a decent scientific reference manager. There are some available, and they're not horrible (even if some are), but none quite match the app I've been using on my Mac, Bookends. I shall probably end up with Zotero (as EndNote is entirely unacceptable), but a wider gamut of choices would have been nice. Same with Ulysses, my authoring system. Scrivener will do the trick, but it's not nearly as nice. Some of these things are personal, of course: objectively, Scrivener is at least as accomplished as Ulysses is, but it misses some key features (the main one being live Markdown parsing) and sometimes seems overly complicated.