I would have to say that the best moment I have had with Lizardmen comes down to two equally enjoyable events
(1) Due to some poor manuvering, my Salamander pack gets charged by a unit of a unit of high elf reavers. They were 6 (or 7?) wide so they were able to lay into my skink handlers, killing all but one. Amazingly, with the strikes back I was able to kill all 6 Reavers with my 6 salamnder's attacks

. The following turn, I shot into a unit of 20 Swordmasters, and rolled 2 10s and 1 8 on the artillery dice. When I came up with exactly 20 4s to wound, my opponent threw his rulebook at me (it was one of the hardback ones unforunately)
(2) The greatest moment I have ever seen in warhammer wasnt exactly done by me, but I was playing in the game with my Lizardmen so it counts

. During the storm of chaos campaign, my local store had a huge 10,000 pt per side team battle. I was teamed with an assortment of elf-ness (woodies, asur, and what someone tried to pass off as asur but were quite blatantly dark elves) against a team that combined 2 skaven teams with a massive store owned Archaon's Horde army. Now the store manager is a huge ___, and had been bragging about how his newly painted pair of Hellcannons were going to destroy our side (he was also trying to get everyone to buy one also at the time...go figure...). On the first turn of the game, we roll off and the chaos and skaven team wins the roll to go first. The first weapon fired is the skaven warp lightning cannon. This little 8 year old skaven player rolls the dice, and misfires.
It turns out to be a strength 10 (d6 wounds) shot, and when he rolls the scatter dice the cannon shoots a beam that goes right through both hellcannons (and 5 chosen chaos knights to boot). Naturally I'm telling this story because both Hellcannons were destroyed in that one shot

. Following that the GW employee lost his temper and started yelling at the little kid. So good.....