The ones that stand out for me are:
1. Clive Allen's 'goal' for Crystal Palace in the 80's that hit the back of the goal and came back out and the ref waved play on
2. Crystal Palace's disallowed 'goal' at Bristol City when Neil Warnock was in charge a couple of season's back; it was same as above, but comes second because I quite liked the fact it happened to Warnock
3. The Reading 'goal' that was given against Watford, that had never gone in at all.
To me these are far, far worse than the Poll incident or a bad off-side.
On Saints related ones, the Kevin Keegan disallowed goal against United, still pees me off even now.
[video=youtube;4HCiBrKjNKE]http://www.youtube.com/watch?v=4HCiBrKjNKE[/video]
[video=youtube;O0YiuSbBdaQ]http://www.youtube.com/watch?v=O0YiuSbBdaQ[/video]
[video=youtube;S9SXa55s2OM]http://www.youtube.com/watch?v=S9SXa55s2OM[/video]