Perhaps plow it into more start-ups like Aviary, a Long Island-based design software company.

Bezos, via his Bezos Expeditions fund, has followed up an investment in the company earlier this year with another slug of cash. It’s part of a $7 million Series B round led by Spark Capital, best known in these parts as the guys who made a very big bet on Twitter, which Bezos also invested in.

If you’re sick of hearing about Web start-ups with just the vaguest sense of a business plan, Aviary may be a refreshing change. It is trying to make money by selling cheap, Web-based alternatives to popular, expensive design software, primarily the stuff that Adobe (ADBE) sells, like Photoshop and Illustrator. Granted, it doesn’t make much money yet: The company only began selling $24.95 subscriptions to its software suite earlier this year.

Down the line, Aviary also imagines it will be able to create an online marketplace where the creative types who use its software can bid on work assignments. Sort of like eBay (EBAY) meets Craigslist meets Etsy meets Amazon’s (AMZN) own Mechanical Turk.

Here’s the full press release:

Aviary Secures $7 Million in Series B Financing Led by Spark Capital

Provider of Creative Application Suite in the Cloud Makes Creation Accessible to All and Advances the Growing Digital Economy

LONG ISLAND, New York (October 26, 2009) – Aviary, Inc., a pioneer of a creative application suite in the cloud, today announced that it has received $7 million in Series B financing led by Spark Capital, with participation from existing investors, including Bezos Expeditions, a personal investment company of Jeff Bezos. With a suite of digital creation and editing software available as an online service, Aviary offers a simple and cost-effective solution for creators of all genres–from graphic design to audio editing – to express their creative talents and participate in the burgeoning market for digital goods. In conjunction with the investment, Mo Koyfman of Spark Capital will be joining Aviary’s board of directors.

“Aviary’s robust suite of online creative tools is fundamentally democratizing digital creation. Whereas the market for digital goods was once reserved exclusively for creators using proprietary desktop software, Aviary is delivering creative applications that allow anyone with a browser to participate,” said Koyfman. “And by doing so in the cloud, Aviary allows for seamless online creation, collaboration, distribution and ultimately monetization previously not possible. The Aviary model has the potential to exponentially increase the number of creators and collaborators contributing to the digital economy.”

Until now, the digital creation market has been largely dominated by desktop software solutions which are often cost prohibitive and involve complicated interfaces. By contrast, Aviary offers a powerful creative toolset in the cloud that enables professional and amateur creators alike to easily create their own digital works. The basic Aviary suite is available for free to users and includes an image editor, vector editor, audio editor and more. Users can also upgrade to the pro suite to gain commercial features such as unlimited private storage, as well as collaboration and community enhancements. For more information, visit http://aviary.com/.

“We are disrupting the status quo by eliminating the long-held barriers to digital creation and giving creators the tools they need to create, market and monetize their vision,” said Avi Muchnick, founder & CEO of Aviary, Inc. “We are extremely excited to have Spark Capital on board. Their broad-ranging internet, software and consumer experience will be a tremendous asset to us in furthering our mission to make creation accessible to creators of all genres.”

Instead, the New York-based company has just raised a $4.5 million Series B round that its CEO, 22-year-old David Karp, says will fund it for two and a half years. Union Square Ventures and Spark Capital, which led the company’s first $750,000 round a year ago, also led this financing. My educated guess is that its investors now value Tumblr at around $15 million.

Tumblr is a “microblog” platform that is supposed to let its users quickly create nice-looking posts with a minimum of effort; it sits somewhere between Twitter and full-fledged blogs like Blogger and TypePad. It is popular with a relatively small but prolific user base: Its 500,000 users have created pages that draw 15 million unique visitors and 61 million page views a month, Karp says.

Money? Nope. Tumblr is free–and has no ads cluttering up its hipster vibe.

Way back in 2007, those kinds of numbers would have been catnip for the likes of Google (GOOG) or Yahoo (YHOO). Now, though, even deep-pocketed buyers aren’t racing to snap up revenue-free start-ups. But Karp says raising money from his previous investors was easy: “These guys came to us with a deal that made us incredibly comfortable.”

Karp says he’s going to start generating money in early 2009. Not by selling ads on his members pages–Karp thinks the site will eventually incorporate ads in some way, but not yet–but by selling users “premium” services, most of which he’s not ready to describe. He does promise they will be “really sexy.”

More practically, Karp points out that other Web services, like the WordPress blogging platform and Yahoo’s Flickr photo service, have been able to upsell many of their users with goodies like extra storage. He figures many of his users will pay up, too.

The new money means he’ll have time to prove his thesis. Karp has just doubled his staff–which means there are now all of six people on payroll. One of them, hired in September, is John Maloney, Karp’s former boss at Urban Baby, where he started his Web career. Maloney is now in charge of business operations.

The money also means there are heightened expectations. Karp has done much more than people twice his age (and has the press clips to prove it). But the newest funding round means his investors think the company will be worth as much as $50 million by the time he sells it or raises more cash. In order to prove them right, he’s got a lot of work ahead of him.

[Image Credit: David's Log]