I've recently learnt how effective kick-swim sets are. A set we did today for instance was:
10x100 as 1-4 50k-50swim, 5 kick hard, 6-9 50k/s, 10kick hard
This type of set i find allows you to work at a high effort all the time without accumulating fatigue as if you were doing 10x100 fr or 10x100 kick on a quick pace time. The switching from kick to swim lets you focus on your legs and then your upper body. One half is always recovering while the other is worked.
Here is something I heard in the news today that might interest you:
A middleaged scotsman fell into a shark infested tank at the Glasgow aquarium. THe man somehow miracoulsy escaped unscathed. When asked how he escaped the man-eaters he had no comment. Later sources however are reporting that the sharks noticed the man was wearing a "Scotland for World Cup 2010", and even the sharks couldn't swallow that.