Investors of every stripe are on the lookout for anything that will give themselves a leg up on the markets. With the advent of smartphones and tablets, investors have turned to technology to gain that edge. As a result, there has been a proliferation in the use of stock investment apps.

Which ones are worth checking out?

There are several stock investment apps I believe can make a difference in your investment success. However, remember that stock investment apps are no replacement for hard work and research. The best investors always do their homework, and plenty of it.

Still, with that in mind, here are five of the most interesting investment apps out there:

Stock Investment Apps — Motif Investing

I’d be a hypocrite if I didn’t put Motif Investing at the top of my list. I’ve raved about the Silicon Valley startup for more than a year, now. Its simple concept allows investors to take real-world investment themes and turn them into actual portfolios.

I’ve created a model portfolio that brings together 16 stocks that were bought (hypothetically, of course) after losing 20% of their value over a one-month period. I’m excited about its long-term chances, and the best part is that anyone can buy it. When it comes to stock investment apps, what you see on your iPhone is pretty much what you see on your desktop except that it’s designed for mobile. It’s clean and simple … just like Motif Investing.

Stock Investment Apps — StockTwits

If you’re trying to figure out which way the wind’s blowing on a certain stock, there’s no better way then to check out Stock Twits, easily the most useful of  the stock investment apps focusing on social media.

Founded by fellow Canadian Howard Lindzon (he now lives in San Diego), the California resident has spent a career building useful websites geared toward investors. You might remember Wall Strip, a funny online TV show geared to investing, that was ultimately sold to CBS (CBS) for $5 million only to be shut down shortly thereafter.

Suffice it to say Lindzon understands what investors are looking for. Like Motif Investing, Stock Twits’ mobile app is simple to use and highly informative, and that’s all you can ask from good stock investment apps.

Stock Investment Apps — CNN Money

Things have changed a little over at CNN Money. Its parent, Time Warner (TWX), split off its publishing division, Time Inc. (TIME), on June 6. As a result, CNN (part of TWX) has taken control of the CNN Money website while its former stablemates Fortune and Money (part of TIME) have started their own websites operated independently from CNN Money.

But iPhone users need not worry. CNN Money is still one of the best stock investment apps for investors looking to keep abreast of the latest business news. AppCrawlr gives the iPhone/iPad app a rating of 4.2 out of 5, which is solid, but what stands out for me is the 94% usefulness rating. Investors want the latest information, and CNNMoney appears to bring it.

The former app was a little confusing with the Fortune and Money articles thrown into the mix. The TIME spinoff has created a stronger, more focused offering.

Stock Investment Apps — Yahoo Finance

OK, I haven’t been the biggest supporter of Yahoo (YHOO) in recent memory but I’m not going to leave it off a list about the best stock investment apps just because I think the company ought to take its Alibaba stake and exit the media business.

Most of us who write about stocks depend on Yahoo Finance as a way of keeping track of all the things written about a particular company. It’s quick, it’s easy, and the Yahoo Finance app ramps that up. It’s especially helpful if you just want to take a quick glance at how your portfolio’s performing.

While iTunes only gives it three stars, I think we all can agree it serves a purpose … which is more than Google Finance can claim.

Stock Investment Apps — Stock of the Day

Last but definitely not least is Louis Navellier’s Stock of the Day app, which provides investors with clear and actionable advice.

Each trading day, investors are given a buy, sell or hold recommendation for one stock with grades assigned from “A” to “F” on fundamentals like sales and earnings growth. You’ll know immediately whether or not to buy the stock in question and the reasons behind Navellier’s conclusion.

Some might be skeptical of this approach, but by using his proprietary Portfolio Grader software, Navellier has been able to deliver superior returns for his subscribers. At the end of the day, the proof is in the pudding. Besides, when it comes to investing, keeping it simple always wins.

As of this writing, Will Ashworth did not own a position in any of the aforementioned securities.