http://calendaz.com (disclaimer: I made it)

I wanted a private calendar without sharing/invites too, so I ended up building my own (do not recommend unless you have a lot of time on your hands!).

No spam, no ads, you own your data. Feel free to email me if you have any questions about it.

They're working on it:

  http://news.ycombinator.com/item?id=3056105
  http://news.ycombinator.com/item?id=3053971

I suspect it's more of a legal/business challenge than a technical one.

Laziness, incompetence, and because the person writing a technical job posting often doesn't understand or value the skillset they are hiring for </generalization>

Reid Hoffman:

http://37signals.com/svn/posts/1718-if-you-review-your-first...

http://venturebeat.com/2011/03/15/reid-hoffman-10-rules-of-e...

http://www.cambrianhouse.com/blog/startups-entrepreneurship/...

http://techcrunch.com/2010/10/16/reid-hoffman-startup-school...

(a response to the controversies regarding the direction for Rails 3.1)

These were a great read. Full recap here:

http://weblog.jamisbuck.org/2011/2/7/maze-generation-algorit...

Any frameworks/libraries that implement these algorithms yet?

Well yeah, we're working on it though the plan is to make it SaaS.

The basic algorithms are very simple; you could implement yourself. Getting great performance is a different matter.

The obvious guess would be coupon codes (?).

Looks like there's a CSS bug on /account/billing - the coupon rows probably shouldn't change background colour on hover.