A new long challenge is up at Al Zimmermann's Programming Contests -- Delacorte Numbers. Find the description here. Neat prizes are announced for two best participants. You must register in order to compete.

The problem seems really cool, so I encourage you to try, especially if you like TopCoder Marathon Matches or something like that.

UPD: http://azspcs.net link doesn't work now. Here's a message from Al Zimmermann:

As you probably know, the AZsPCs server died on November 13th. Then, during the effort to transfer the site to an external host, the AZsPCs domain names (azspcs.com and azspcs.net) became stuck in registrar hell.

In order to allow the contest to continue I've borrowed a domain name. AZsPCs is now located at http://trdb.org and will remain there until January 17 (which is two weeks after the end of the current contest). As soon thereafter as possible, the site will return to azspcs.com and azspcs.net.

Best regards, Al Zimmermann