The 'blogger over at Catholicland traces the geneology of the Caesar's Bath meme. I don't think I've ever been accused of begetting anyone before.
The whole thing reminds me of the tracing of Episcopal lineages (isn't the Apostolic Succession great? ;) ) and there's a very interesting page dedicated to this. The ever-useful Catholic Hierarchy page also includes a lot of Episcopal lineage information. It doesn't take too much reading to discover that many of the same names keep cropping up and the 1st referenced page above explains that more than 90% of Roman Catholic Bishops can trace their sucession to Scipione Cardinal Rebiba (ordained 1541) via Pope Benedict XIII. Interestingly, in the period since 1550 there are only 4 Popes about whom we lack information regarding their consecration.
Link to Bust of Benedict XIII
Lineage of Pope Benedict XVI
The Dutch Touch
It doesn't take much searching on the web to find many schismatic bishops who have also compiled Episcopal lineages through ordination by Old Catholic bishops. I shan't link to any, but I recall one chap who claimed to have episcopal lineages linking him a whole collection of Churches and denomincations. (Roman Catholic, Old Catholic, Eastern Orthodox, etc...)
Notable however is the case of the Anglican Communion (whom I do not put into the same category as the rent-a-bishops mentioned above), some of whose bishops may well be validly ordained. Leo XIII's 1896 Bull Apostolicae Curae ruled that Anglican Orders were invalid as the Apostolic Succesion had been compromised at the time of the Reformation due to defects in the Anglican ritual. However, since the 1930s Old Catholic bishops have participated in the consecrations of Anglican Bishops and this so-called 'Dutch Touch' opens the door to their orders possibly beinf considered valid. Interestingly, this page claims to track Archbishop George Carey's (now Lord Carey of Clifton, emeritus Anglican Archbishop of Canterbury) lineage back to Pope St Nicholas I!