There have been a lot of great plays in LSU history, but two stand out to me. Billy Cannon's Halloween Night Run, and Warren Morris's "shot heard round the bayou!". http://www.baseballamerica.com/today/leagues/NCAA/03cws_mm1.html That link has a great write up on the event, and another great Tiger moment is just below it. Each was a GREAT individual effort in its own right, but for the time that it occurred, and what was on the line (a national championship), those two stick out in my mind over the 50 odd years I've been a Tiger Fan. OK, I cherry picked. You can add your favorite big plays now.
Those were definately great moments. But dont underestimate the newer ones, like the bluegrass miracle or the ASU 4th down 50 yard (on the run) strike or the Holiday return.
depends what you mean by "great". sounds like you mean significant, in that case you cant beat plays in nc games. otherwise, i remember a great kickoff return td by kennison (>100yds)--dont remember who it was against. a great td run by cecil at msu when he lost his shoe. wait, maybe he got caught from behind. the 2pt conversion fumble return vs vandy for the win by hankton? hilliard (ivory)? run by alley against iowa catch by kinchen in the endzone @ vandy to win the game that was called back bc of crappy off pass interference call.
If we're talking about football only, Hodson to Fuller (Earthquake game for those who don't know) stand out for me because that was my first game in Tiger Stadium. Second, Marcus Spears' pick/six in the NC game. Third, Warren Morris homerun.