Re: CMS suggestions
Well, you could add something like that to any of the CMS packages out there, but what's the point? There'd be a lot of interweaving and patching-in and all kinds of nonsense for no real gain (unless you want to call out your housemates on your blog, of course -- a real-time/run-time kick in the back pocket for anyone who's running a little late as a call-out box in mid-rant). All you need in the blog/CMS is a link to the app, really -- and, while it might make absolute sense to have a separate database, there's no reason why you can't add a couple/three namespaced tables to your CMS's db.
What you want is a sort of QuickBooks Online deal, but without all the tedious payroll stuff. A general-purpose home budgeting kind of deal. Sounds like what they'd call a pretty good MVP (minimum viable product) in the start-up world. All you need is a plan, and the ability to execute it. How're your programming chops? It doesn't sound like it would be too terribly difficult to put together, even if you want a nice, responsive AJAX-y front end. Heck, I'd be tempted to do it myself if the terms were right (as regards the future of the project, not payment up front).
“Beware of bugs in the above code; I have only proved it correct, not tried it.” --Donald Knuth
"It was as if its architects were given a perfectly good hammer and gleefully replied, 'neat! With this hammer, we can build a tool that can pound in nails.'" -- Alex Papadimoulis (on TheDailyWTF.com)