The good folks at On-Demand education have setup an online Quiz to commemorate the 20th Anniversary of Siebel. There competition seems fierce, till last week I saw only 30 names on the leaderboard, now it’s double that. The questions are from everywhere, technical and functional Siebel thingies and some history. You can find some of the answers of the questions on @lex’s awesome Siebel site, and he was involved in setting up of the questions.
The page is still open, but the correct answers are not disclosed. So go ahead and give it a try !