I am seeking to apply the "easy data entry" + "subjective good/ok/bad" measures to help folks discover patterns of bad spending decisions. While most every budgeting/spending app will show you "how much you have left" or "safe to spend" the real measure of improvement is whether you made good decisions or bad decisions given your life circumstances. This also has the effect of softening the penalty for missing data. If you miss some data, you just pick up where you left off. You're not trying to balance your budget. You're tracking decisions. Although I'm not (yet) biting off the notion of correlating it with other personal analytics, that's an interesting extension of the idea.
I'm really convinced that a behavioral approach to spending/budgeting would lead to longer lasting positive changes than fretting about exceeding your grocery budget by $19 due to unexpected company joining you for lunch.
The general gist is described here: http://www.spendlight.com/land-3.html