UPDATE: This is all pretty much subsumed by http://blog.beeminder.com/commitwall
This is a compromise between requiring a credit card to sign up and not.
We’ll add the following to the sign-up page:
Beeminder is a community of seriously awesome and ever-improving, often overachieving, humans. To sign up, we ask you to prove you’re serious (and human) in one of two ways:
(1) Enter a credit card:
(you’ll need to do this eventually, unless you never ever go off track)
Or, (2) write one or two sentences (we read all these) about how you found us and why you think you may benefit from Beeminder’s bizarre brand of self-quantifying, self-binding lifehackery:
(stating your intentions up front also helps you stick to your commitments)
I snagged twitter handle @bsignups in case we want to autotweet those (or semi-automatically tweet them).
Thanks to Alys for the idea to make the statement of intention meaningful by framing it as helping you stick to your commitments.
-) Makes Beeminder seem more daunting/intimidating than it already is +) Calibrates expectations that beeminding takes consideration and commitment -) Any hurdle deters some people who may eventually have become fans +) Weeds out non-serious or clueless people so we can focus on our ubernerds -) More users, serious or not, means more exposure, more buzz, reaching more people +) Encourages/incentivizes adding a credit card => Beeminder more effective +) The act of stating one's intention may make for more effective beeminding +) Statements of intention would be wonderful data and feedback for us +) Having those intents to refer to makes helping confused users in support easier +) Allows proactive support for people who've misunderstood what Beeminder's all about +) Could almost eliminate spam signups, the bane of our statistics
Related: Reassuring webcopy about why you can trust us with your credit card
Patrick McKenzie of Stripe points out that “free trials [have] astonishingly low conversion rates; you need a sophisticated marketing engine harvesting a lot of attention at scale to make these work.” (He also argues that your really good customers actually feel reassured when you charge real money.)
The big downside of the commitwall is losing people who are stingy/scared at first but would’ve eventually warmed up and paid us. (Corresponding upside: losing all the people who would never enter a credit card anyway, currently 90% of signups.) But I think the most important argument for commitwall is that the moment of the person wanting to sign up is an extremely good time to convert them. Even with hypothetical perfect lifecycle emails, it’s hard to top that. The one thing we gain by waiting is that later they’ll have had the chance to try Beeminder. That’s worth it only if we can exceed their expectations. But with our years of history and passionate community and nothing but love for us all over the internet, the expectations are hard to top. Not to mention that beeminding without a credit card is toothless and dumb and is a horrible introduction to what beeminding is supposed to feel like. So I predict the probability that we get a credit card only goes down after signing up. There are plenty of exceptions but that’s my prediction in aggregate.
It’s especially true since, if you only create 1 or 2 goals, the point where we require the credit card is after you derail. That’s bad. People stick their head in the sand at that point. Also it’s preposterously common for users to not have paid attention and not understand that they don’t owe money and aren’t getting charged when they put in the credit card at that point. We make that perfectly clear in the webcopy but users absolutely do not read webcopy.
(Counterpoint: If that’s a big factor then commitwalling after 2 goals instead of 1 goal should be worse. Why? Because presumably (I haven’t checked) if you get an extra goal without adding a credit card then you’re more likely to be forced to add a credit card due to derailing rather than due to adding an extra goal. But as we’re about to see, it’s neither worse nor better. I think it’s true that requiring a credit card upon derailing is very bad, just that commitwalling at 1 vs 2 goals doesn’t affect that all that much.)
The commitwall is currently hit after either 1 or 2 goals, bucket tested. If you think that having more time to try Beeminder helps turn users into customers then you’d predict that being commitwalled after 2 goals is better than after 1. This is not the case. The probability you’ll create a 2nd goal naturally goes down (but only slightly, from 34% to 31%) if we commitwall you after 1 goal. But revenue doesn’t go down detectably at all. Of course, commitwall before creating any goals is very different from commitwall after 1 or 2 goals, and it could be worse. But I predict it will be better.
The fear and friction of adding a credit card is surprisingly low. In fact, we keep seeing users who are surprised that they hadn’t already added a credit card, seeming to have presumed that it wouldn’t have made sense for Beeminder to have let them start beeminding without doing so.
Another advantage of commitwall is that by eliminating the 90% of users who won’t enter a credit card, we can put real human attention on the remaining 10%. We can also still capture email addresses of some of the 90%. 
One more advantage: If you find Beeminder frustrating and confusing and haven’t entered a credit card yet, you’ll tend to walk away. If you find Beeminder frustrating and confusing and you have entered a credit card, you’ll tend to talk to us and become a convert for life.
If you’re (rightly) nervous about handing over your credit card number, this is the part where we solemnly promise you won’t ever be charged due to any kind of technicality, including confusion about the rules. (You won’t be charged at all if you stick to what you’re committing to!) We’re pretty sure that 5 minutes of googling around to see all the gushing about us on the internet over the last 7+ years, plus our blog and the Beeminder forum, will convince you that that promise is credible.
 Just talking about the commitwall where we make you enter a credit card or payment info, not talking about eliminating the free, non-premium plan. No paywall, in other words.
 We can capture an email address for everyone who doesn’t make it over the commitwall if we get the email address before mentioning the credit card. Would that be insufficiently transparent and the user needs to know everything they’ll be asked for up front? I actually like how Slack requires you to confirm your email address before showing you anything else whatsoever. They’re saying everything else is a waste of time until we verify that we can communicate with you. Which is very much true for Beeminder.