I've not, but my Mum has has quite a few. She had a bad fall down the stairs at home and broke her neck, another bone further down her back and bashed a hole through her skull (so did a good job of it). She had to have loads of different scans and tests, including several MRIs over time. She said it is a little strange as you can feel the pulse of the magnets, but nothing bad.

Interesting that you have a lump in your neck as I also have one on the right hand side of my neck. I went to the doctors when I first noticed it in my teens and he just said it was a gland that probably was more susceptible to infections. However it has always remained feeling fairly solid/hard. So I will be interested to know what they find out with you. What did you have done last year?