I just spent five days researching how to generate PDFs dynamically or alternatively how to fill PDF forms dynamically from a server-side script. Just so anyone who purchased a ticket to our concert can print it out themselves (the ticket will include a barcode which can be scanned using a mobile phone with Java and a camera).

Then it dawned on me that I could simply point them to a (HTML) page which they can print out. Believe me, I felt stupid.

(But at least I learned about PDF forms, (X)FDF, and JavaScript in PDFs. Oh well...)