Mergers and acquisitions are tough to predict -- but that doesn't mean it's not fun to try. There are a lot of business marriages that make sense from a strategic or financial perspective. Here are three I think would make all the sense in the world.

Toyota buying Tesla Motors
Toyota (TM -3.23%) is well on its way to recovering from challenges that hit the company from 2009 to 2011, when market share fell four points. The company now has 14.1% share of the U.S. market and updates to the RAV4 and Corolla are coming this year, so the solid and dependable lineup appears to be faring well in the improving economy. But what Toyota doesn't have is sex appeal.

Tesla Motors (TSLA 4.96%) could change that and bring a whole new feel to the company. Tesla is already supplying drivetrains for the RAV4, so there's a relationship between the companies. We also know that Toyota is willing to take technological leaps forward, as it did with the Prius, creating early dominance in the hybrid market. Tesla could do the same for electric cars, giving Toyota credibility that General Motors, Ford, and Nissan haven't been able to gain in early electric efforts.

I'm not sure Elon Musk would be excited about a deal, but a few billion dollars could change that. Tesla currently has a $4.37 billion market cap and a 50% premium would cost about $6.55 billion, or $57.68 per share. For Toyota, I think it would be money well spent and for Tesla it would take a lot of risk out of the way before ever earning a dime in profit, plus get a great price for shareholders.

Comcast buys up content
The real reason Comcast (CMCSA -5.82%) bought NBC Universal from General Electric (GE 1.30%) is that it needed to. Cable is a dying business and Comcast knows it. Hulu, Amazon, and Netflix are all encroaching on territory once owned by cable, and there's no looking back. Buying NBC Universal gives Comcast content that will stave off a switch to streaming for some customers and give it content to sell via streaming when the time comes. But it can always use more content.

Comcast is up against media giants like Disney, Time Warner, and Viacom, which own a vast majority of the content we consume. If Comcast added DreamWorks Animation to its stable, it would get two or three full feature movies per year, a number of television shows, and all of DreamWorks' past content. For $2 billion or so, that could end up being a steal.

With DreamWorks' stock trading near a 52-week low, I don't think investors would oppose a deal, either. Comcast needs more content and DreamWorks would love to find a buyer so it isn't all alone in a world of big media. This deal makes all the sense in the world.

Microsoft needs the cloud
The new Windows operating system has done a lot to bring Microsoft (MSFT -2.45%) to a somewhat level playing field with Apple and Google, but it still has a long way to go in convincing users it is an easy and intuitive platform. What would change that? How about buying Dropbox?

Microsoft has SkyDrive, which isn't terribly different from Dropbox, but Dropbox has a huge head start on Microsoft's cloud efforts. If Microsoft bought Dropbox, it could fold SkyDrive into Dropbox and add a recognizable and trusted cloud name to its arsenal. Want a new phone? Ohh, this Windows 8 phone has Dropbox; I know that, so it must not be too bad. 

It would also vault Microsoft ahead of Apple in use across platforms. I use Apple devices, but the iCloud is limited in what it will take and isn't friendly to regular files I may want to back up. That's why I have Dropbox on all of my Apple devices. Don't tell me Microsoft being one of the more popular apps on iOS wouldn't make Apple executives cringe just a little bit.

So, what would it cost? The latest data has Dropbox's value at just over $5 billion, but Microsoft would have to exceed that. I think $10 billion may get it done, a drop in the bucket for what Microsoft would be getting, if you ask me.

Foolish bottom line
Will any of these deals happen? It's unlikely, even though strategically they make a lot of sense. For now, I'll dream of these deals becoming a reality.