(CNN) -- Marco Arment's salesmanship could use some work.
To complement the one-time $5 fee he charges for his popular mobile application called Instapaper, Arment added a subscription service in October. And what does the $1-per-month plan get you?
"Right now?" reads the question-and-answer-style come-on. "Almost nothing, except knowing that you are supporting the Instapaper service's operation and future feature development."
Not exactly a Steve Jobsian pitch, but Arment, whose iPhone and iPad apps for accessing news articles offline have more than 1.5 million registered users, has found takers. He declined to say how many people subscribe, but "it's enough to pay for all my servers."
"I thought I would have to offer a lot more," said Arment, who recently began testing new integration for Kindle users exclusively with subscribers. So that's something. "I knew I'd have a lot of goodwill out there, but I thought people would need more of a bonus," he said.
Instapaper's subscription-cum-donation model has inspired others, especially those in the online-writing world, to follow suit.
Longreads, a website and popular Twitter feed that links to lengthy articles chosen by editor Mark Armstrong or readers, added a subscription service last month.
Because Instapaper is designed to strip distracting elements from Web pages, the two services often go hand in hand, and Longreads has buttons below each link for sending them to an Instapaper reading list. Also like Instapaper, Longreads' membership program offers little more than a warm-and-fuzzy feeling.
"I wanted to emphasize that this membership is something people can choose to do mostly to support the service," Armstrong wrote in an e-mail. "We think our membership perks will grow but don't want to over promise."
People who pay $3 per month will eventually get to test new features first. Paying $30 annually gets you a travel mug emblazoned with the logo.
Longform, a similar site with a similar name, allows for one-time donations. Quaint.
Donation buttons have long been a common occurrence in Internet and computer software. Developers have a name for it, "donationware," which generally offers a full version of the program with an unintrusive request for one-time donations.
But perhaps thanks to the proliferation of the "freemium" model, which gives a feature-rich app for free and then charges for power-user features, and of online subscriptions, such as Audible, Netflix and Spotify in Europe, recurring donations are starting to catch on.
They're giving podcasters a flowing revenue stream. TWiT founder Leo Laporte, who runs a network of advertising-supported Internet shows, takes his salary from fans' recurring donations. No Agenda, an online program co-created by podcast pioneer and former MTV personality Adam Curry, asks listeners to donate $50 a month.
A framework called Kachingle gives website owners a button to allow visitors to easily leave tips with a couple of clicks.
Readability, a service similar to Instapaper, also added a subscription program, but the idea is that 70% of each subscriber's monthly fee (the minimum is $5) is divided among the writers and media organizations the user reads the most.
However, the publisher doesn't get its cut until signing up for an authorized Readability account. Some publishers, such as the Slate Group, have indicated that they would not bother unless the amount is substantial.
Readability keeps separate escrow accounts earmarked for publishers and does not dip into those funds, creator Richard Ziade wrote in an e-mail. More than 1,000 websites have signed up to be considered for royalties, he wrote. He declined to say how many subscribers Readability has, which publishers are on board, how much money has been paid out, or how much is on hold.
In essence, the only guaranteed payout is the 30% that goes to Ziade and the New York developers who maintain the service.
Arment, who designed a mobile app for Readability that was never released due to disagreements with Apple over financials, echoed the idea that Readability's business would not make much of a mark on big publishers' balance sheets. (Apple, by the way, also rejects apps that solicit donations.) While media conglomerates like the New York Times account for the most-saved items on Instapaper, they're only a faction of the overall publishers being read through the service, so the payout wouldn't be huge, he said.
Last year when Instapaper began to pick up steam and revenue, Arment left Tumblr, the fast-growing blogging company he co-founded, to focus full-time on his reading tool. (He's also an advisor to Readability.)
With Instapaper's recurring app donations, members are charged $3 every three months. (Arment needs to charge at least $3 in order to cope with fees imposed by PayPal, he said.) One guaranteed perk allows subscribers to turn off the small text ads on the site.
Arment felt compelled to call it a subscription service rather than donations, even though he agrees the perks aren't strong.
"If you call it anything else other than 'subscription,' I think you'll get a lot of angry people when it automatically renews itself," Arment said. "I don't want to trick anyone into paying me. It's $3. The reality is: if you don't want to give me that $3, I'd rather not take it from you."