If anyone has a good idea for a non-existent iPhone/Android app then let me know. I could try making it.
If you can write for Windows and Windows Phone, send me a PM.
I could do Windows/Windows 8 but I can't currently do Windows Phone.
The way I'd be making these apps would be, instead of me writing them in a native language, I'd be writing them in a program called GameMaker. GameMaker is intended to be used for making computer games but it can be used to make other stuff besides games. So I can make regular apps without much problem (except there are a few limitations, e.g. I don't think GameMaker can be used to write a program that uses the phone's camera or microphone). Anyway, I've been using GameMaker for several years so I'm pretty familiar with it. And one of the features is that once I make the app in GameMaker then I can export it to Windows and Mac and iOS and Android and Windows Phone and whatever other platforms GameMaker lets me export it to without really changing the code much. However, I have never actually exported a GameMaker project to any of the mobile devices before, so I'll have to experiment a with exporting it and see if I can get it working on the various platforms. (Which is why I said I can "try" to make it, but I really can't guarantee I'll be able to.)
The reason I cannot currently export to Windows Phone is because each of the platform-export things costs extra and I haven't yet paid for the Windows Phone export (the regular Windows and Windows 8 exports come with it and I've already paid for the Android and iOS exports). Maybe I will eventually purchase the Windows Phone export but maybe I won't (I'm really not a fan of Microsoft). Either way, I don't currently have it so I can't make stuff for Windows Phone at the moment.