OMG! This is my Wall of Shame! There aren't too many things here I haven't owned, and it's painful to think how much money I could have used for fabric--or donating to good causes.
I have a Viking Designer SE and am very happy with it, but I feel guilty for never using the embroidery capabilities and 90% of the stitches. Just gave the Altos2 away after close to 10 years. I've never had any luck with rotary blade sharpeners. Max Throat (mentioned 'way earlier in this thread) was not only an expensive mistake, it actually kept me from finishing quilts for two years as I was DETERMINED to get it working (how dumb is that??).
And then there are all the things I'm going to use "someday": PaintStiks, fabric dyes, specialized sewing feet...