When investing for the long term, not only do we like to see a very nice track record of growth and prefer a nice dividend, but we also like to see that the companies we invest in are still capable of innovation.

With that in mind, here are three companies who could transform the financial sector over the next few decades, and could make their investors a lot of money along the way.

Over 150 years of innovation and still going strong
Ever since Diebold (NYSE:DBD) began making bank vaults and safes in 1859, the company has been an innovator in the banking industry. Currently, Diebold makes ATMs and other self-service systems, security systems, and software products.

And, the company has big ideas for the future. With the recently revealed Responsive Banking Concept, Diebold is planning to help banks increase their physical footprint while cutting costs at the same time. Basically, the company's concept is for an unmanned, self-contained bank branch in a very small space, which would minimize the banks' labor costs and eliminate the cost for large facilities.

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Diebold's Responsive Banking Concept . Source: Diebold

And if a bank has one branch in a medium-sized town, they could replace it with four of these, making it more convenient for their customers and more cost-effective.

Most news headlines about the future of banking involve mobile and online services, but Diebold thinks that similar cost savings can be achieved while maintaining a wide physical reach. After all, no matter how much the technology evolves, some people just want to go to the bank.

Diebold is also a very high-quality dividend stock. In fact, Diebold has a longer streak of consecutive annual dividend increases (60 years) than any other publicly traded company. And the fact that a company with such a long history is still capable of innovation is a very positive sign for investors.

A winning business model that should make the big banks take notice
BofI Holding
(NASDAQ:BOFI), better known as "Bank of Internet," provides the same banking services to customers that most commercial banks do. The company offers checking and savings accounts, lending services, business banking, and more.

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Source: company

The difference is that the company does it without any physical branches whatsoever. In fact, all of BofI's operations are contained in one single location. BofI is a true "Internet bank."

And the numbers suggest this business model works. Because of the cost savings associated with having no brick-and-mortar branches, BofI is able to entice customers with higher interest rates on deposit accounts.

At a time when savings accounts at many of the big banks are paying just 0.01%, BofI is offering 0.61% on savings accounts. While still low by historical standards, it is 61 times what some other banks are paying, so it is a nice competitive advantage.

BofI simply can do more with less. The bank has produced a return on equity of nearly 19%, which is in the 95th percentile of all U.S. banks. And BofI runs at a 31.2% efficiency ratio, better than all but 2% of its competition, mainly thanks to spending less on things like facilities and salaries. In fact, BofI's noninterest expenses were just 1.38% of assets, as compared with an average of 3.17% for banks of similar size.

While I don't think physical branches will disappear from banking anytime soon (this is why I like Diebold so much), BofI has definitely figured out how to make money without them.

Convenience attracts customers
Ever since it acquired Commerce Bancorp in 2008, TD Bank (NYSE:TD) has adopted its philosophy of being "America's Most Convenient Bank."

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Source: Wikipedia

TD's branches are open early, late, and on the weekends (even on Sundays), and offers services like coin counting absolutely free. Customers can even bring their dogs with them to do their banking, and 24/7 live customer support is available, as are cutting-edge mobile and online services.

This business model of "convenience" seems to work. Before it became part of TD Bank, Commerce Bank grew from a single branch in Cherry Hill, N.J., in 1973 to a major player in the New York City, Philadelphia, and Washington, D.C., markets.

And since the 2008 acquisition, TD Bank has done very well. The bank has grown its assets by over 80% since 2008, and demand deposits (checking and savings accounts) have more than doubled.

Plus, thanks to a healthy business model and a high-quality asset portfolio, TD Bank never got into much trouble during the financial crisis, like many of its peers. In fact, not only did TD Bank not have any money-losing years, but its dividend was never even cut. (Note: TD Bank pays in Canadian dollars, so the U.S. equivalent has fluctuated up and down at times.)

Basically, an investment in TD Bank is a bet on the fact that people like being able to interact with real, live people when doing their banking, and that they don't always want their bankers to keep, well, "banker's hours."

Which to buy?
This is by no means an exhaustive list, and there are lots of innovative companies in the financial sector. However, these three jump out to me as having particularly unique ideas that could really pay off in the long run.

The right one for your portfolio depends on a few factors, like your risk tolerance (BofI is riskier than the other two) and your income expectations. However, if you have a reasonably long time period to let your investments play out, you really can't go wrong with any of these.

Matthew Frankel has no position in any stocks mentioned. The Motley Fool recommends BofI Holding. The Motley Fool owns shares of BofI Holding. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.