Online money management site Mint has launched a new Web site that takes aggregated, anonymous spending data from its four million users and turns it into trends, charts, and rankings. And this is a really cool idea — but unfortunately the search function is horrible and makes me want to rip my hair out. But if you’ve got a unique enough search term you may want to give it a try at http://data.mint.com/. It’s in beta.

You can either search by keyword or select a location. (The location selections seem a little odd — there are only two available in Massachusetts and six in North Carolina? And North Carolina offers Fayetteville as an option but not Wilmington or Asheville?) For example you might select Boise, Idaho.

Mint Data will give you a chart showing purchase and expense trends (the expenses are divided up into four broad categories — Travel, Food & Dining, Shopping, and Auto & Transport.) Beneath that you’ll get charts of the most popular merchants for given categories, average purchase amount, and rank.

You can also do a keyword search, but this is where it gets frustrating. Mint Data seems to be defaulting to OR, with the most relevant results at the top, and it doesn’t seem possible to restrict results to a particular area. For example, I’m looking at information for Boise. I want to search for pizza locations in Boise, so I enter pizza in the search box. And I get results from all over everywhere, but not in Boise.

A better example of this is searching for New York Pizza. If I do a search for this, my first result will be a pizza place in New York. But that’s followed by a pizza place in Atlanta, Georgia, and then by places in DC, MA, TX, AZ — you get the idea. I can’t figure out how to search by location. (I tried searching for a specific address but that only made things worse.)

Which is a shame but individual business information is fascinating. Let’s take Wow Bento and Roll in Los Angeles:

You’ll see that you get notes about how popular the restaurant is compared to other restaurants, the average purchase, how it trends over time, and how it compares to other restaurants in the same city. If I’m a business owner, I would be loving this (assuming I could find my business in Mint Data’s incredibly frustrating search engine.)

It’s also interesting to compare to other purchasing information about the same business. Several months ago I noted that Google Places was showing average user spend per month. That information disappeared for a while, but now it appears to be back (it is not, however, available for all businesses.)

It’s interesting: Mint notes that the average purchase for Wow Bento is $10.62. Meanwhile Google Places notes that the average purchase at the same location is $12.30. As far as I know Google has yet to say where that data is coming from, but its numbers are decidedly higher.

Business owners could find a wealth of data about their own stores and competitors in Mint Data, but it needs to be a lot easier to search.