[1] Not even GNU cash gets this right. See: http://www.mathstat.dal.ca/~selinger/accounting/gnucash.html
Where most online tools fail is with investments. Especially real estate (rentals in my case), which is where most of my money is allocated.
More than simply building a savings account, the other side of the coin is making your spending more meaningful by reducing impulsive buying. Saving a few bucks here and there with coupons or promotional discount is way too easy to spoil with just one thoughtless purchase.
Also, I want a single place to see my networth as it's a huge factor in understanding my progression towards retirement. Having multiple interfaces makes this difficult.
I don't log in much nowadays, but I remember it is pretty easy to add asset values and get them figured into net worth. You have to keep manually-input stuff updated, of course.
Several of the companies that offer bank feeds ("add your account") use Yodlee's data.
If anyone is interested in an account with us for user research, leave a reply. It's normally $100 a year. I'll circumvent that.
Really, there's nothing out there for the power user. I believe that market would pay for a good product that doesn't try to push stuff on them (ahem... wealthfront).
If you're looking for a user with real estate assets, I'd be interested in helping by being a tester.
We (HelloWallet) are much more focused on holistic financial wellness. But we are working on some very exciting investment-oriented products as we speak.
It still would be interesting to get your perspective if you want to create an account:
https://my.hellowallet.com/PublicHWWebApp.html?p=hackernews#...
https://my.hellowallet.com/PublicHWWebApp.html?p=hackernews#...