You sound like a lot of engineers I know: you devalue your own time/expertise and are not comfortable with charging for it. I strongly suggest that you move past this hangup.

It isn't "pretentious" to sell things to people who want to buy things from you. It also isn't hard -- if you can set up a Paypal account to take donations you can just as easily set up one to take purchases. I recommend e-junkie, they'll automate the recordkeeping and license key delivery for $5 a month.

You won't make any money that way. I know a guy who does that - he makes $300 a year. By charging for less useful stuff, I make more than $300 a day.

Just add some small feature like adding todo by email and make a pro version and charge $5. The people who love your app will glady support you. When you spend more than 2 weeks on a feature, put it in the 'pro' package. Take a look at how todoist.com is doing it.

I have a site that's a utility for World of Warcraft players (pugchecker.com). It sees about 2,000 uniques a day, give or take, and I've had a donation button at the bottom for a few months now.

In that time, I've received four donations for a grand total of $45. That's a little more than what I see for one affiliate sale using banner ads on the site.

It can't hurt to ask but I wouldn't expect much in the way of financial returns from donations.

Looking at the screencast, it looked very well done and beyond basic. I think you are selling yourself short when you say it's basic and not professional.

However, there are a ton of to-do apps -- many are free. I paid for the one I use because it's an iPhone app (Things). "Remember the Milk" is an example of a to-do app that has web and iPhone integration (and I think charges for both versions).

Off the top of my head, your niche looks to be non-engligh todos (in particular, Portugese). There are a lot of free to-do apps, but maybe yours is popular in Brazil simply because of that edge.

Start charging -- make a free plan that limits the number of to-dos so that people can still try it out and get some value. All current users should probably get the full version for free (for being early adopters) -- or at least of level that is equivalent to what they have now.

The site looks good. The screencast ( http://tu-dus.com/files/screen_pt.swf ) explains things well even though I did not understand the language.

I have no first hand experience in receiving donations (tried, but failed). I have heard from other people that the 0.01% to 1 % of your visitors will donate depending on your audience and your campaign.

If I were you, I would not expect a business to be sustainable based on donations alone.

One of the success stories of this business model is probably cyberduck (http://cyberduck.ch) I have heard from friends that the guy makes decent money with his "donation"-business model. Though it's more like shareware than actually just placing a donation button on your website.

I don't believe in the free or donation based model. You should always charge for your web apps, even if it $0.99/month. You should charge.

clicky: http://tu-dus.com