5 Startups to Watch at Y Combinator's Demo Day An investor's preview of the companies that have caught his eye at the Californian accelerator's summer event.

On August 19, 85 startups will pitch their businesses to a group of influential tech investors at Y Combinator's Demo Day. It will be the largest graduating class ever for the well-known Silicon Valley startup machine.

Speaking from the perspective of an investor who attends events like these periodically, I find these types of gatherings rather grueling. It's difficult to keep track of all the companies as the entrepreneurs rapidly ascend the stage, pitch their startup idea only to be replaced moments later at the microphne by another founder with yet another amazing idea. I've tried taking notes (which is helpful), but there are always companies that you miss if you become distracted.

I've also found that it can help to know who will be onstage before the event organized by the accelerator, so I've assembled my list of five companies that seem particularly attractive to me:

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1. Bayes Impact

I'm a huge fan of nonprofit startups, not just for tax reasons but because they make me feel better about the work I do each day. Bayes Impact is one. The San Francisco-based nonprofit connects data-science teams to organizations working to solve some of the world's biggest social problems. The founders say that the massive use of big data in Silicon Valley (and I would imagine everywhere else) now can be used to positively influence communities of every country.

Bayes Impact chooses to work on only a few issues at a time, relying on a group of full-time fellows. Detecting fraud in microfinance projects, curbing prison overcrowding and optimizing the dispatch services for emergency responders are among the current pursuits.

My take: I like this organization because I believe that big data can be leveraged to solve social problems everywhere. These guys just might be at the forefront of that movement.

2. Beep

Beep makes a device of the same name that lets all the music-playing services in the house be connected to a speaker system and controlled by one dial. Speakers are connected to a Beep by cables. Music can be streamed from mobile devices and Pandora by connecting wirelessly. As a result, it's possible to enjoy music from any source and adjust the volume from one spot.

My take: I like the idea that this is compatible with Pandora and that the company is striving to work with to other music services. As with everything, though, its success rests with the execution.

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3. BitAccess

The founders of BitAccess believe that Bitcoin is the future of digital money and want to give people across the world safe access to it. The company makes Bitcoin ATM machines. It works like this: Someone deposits cash to receive a digital wallet with the equivalent amount in Bitcoin currency. It also works the other way: A person can withdraw cash from the Bitcoins in his or her digital wallet. The company headquartered in Ottawa, Canada, has provided ATMs in six countries.

My take: There's no doubt in my mind that Bitcoin or something like it will play a significant role in the future of the world. I'm bullish on the idea of making cryptocurrencies more available to the public.

4. Traction

Lets say you need an social-media expert for a marketing campaign. Traction's platform lets you enter the type of marketing service desired, the target audience, budget and other basic information. Then it's possible to connect to digital marketers across the world who could help you achieve your marketing goals. You can launch multiple campaigns and compare them. Several big companies are already using Traction, including Danone and CBS.

My take: As someone with experience in pay-per-click campaigns and marketing in general, I'm always on the lookout for ways to optimize my efforts. Also, these guys have an unusually large number of Fortune 100 companies signed up, so that caught my eye.

5. Product Hunt

According to Gigaom, Product Hunt offers what's been described as a kind of "Reddit for any product." Its platform allows invited members to share with its online community their takes about new, interesting products. Just like on Reddit, users can comment, upvote (give a favorable rating) or downvote a listed product. It's generating interest ahead of Demo Day as companies look for new ways to market their products online.

My take: I've spotted on the site tons of products, whose creators I know personally. It's a good sign to me when I see things that I know and am familiar with.

I'll be honest, whether I'm at 500 Startups, Techstars, Y Combinator or just some community pitch event, I become exhausted listening to all the pitches. If you attend one of these events and feel bombarded, look for key points such as impressive user metrics. Always try to capture just how every company relieves a consumer pain point and write it down immediately. Put a star by the companies whose entrepreneurs you'd actually like to meet. Whatever you do, enjoy yourself and have fun along the way.

Related: 10 Questions to Ask When Applying to a Startup Accelerator