mmm a few too many things. Let's see, off the top of my head:
- spoke repair kit* (never ever used but was well reviewed

- touring cassette remover tool thingy* (like a hypercracker, never ever used)
- a thingijamig derailleur accessory (remember those? Useless and unnecessary)
- chain cleaner tool (I was even told at the shop not to get it as it wasn't very good, and that taking the chain off and shaking it in a plastic bottle full of alcohol was far better, but did I listen? Used it a couple of times, realized they were right and made sure all my chains had quick links from then on)
- almost any cyclocomputer (I used to enjoy seeing my average speed, distance, etc, but then I realized I just wanted to cycle and enjoy myself!)
- pedal straps (useless; once I went clipless which was pretty much a week after I got them, they were a complete waste of time. Gave them away)
- any cycling clothes that would have fitted me ten years ago (self explanatory there....)
I'm almost tempted to add an Airzound, but I have at least used it. It's more a case of forgetting to put it on the bike and realizing 99% of the time I didn't really need it. I bought it in haste after having so many cars pull in front of me I thought it would be a good idea.
*to be fair, if I had to use these, they probably would be very handy!