1. Being interested in trains, or building model train sets.
2. Quilting and embroidery.
3. Astrology, where you're truly into the zodiac and pay attention to it.
4. Scrapbooking. If anything, people use apps and do it virtually now.
5. Home brewing. That one's a little surprising, because there was a pretty big home-brewing boom a while back. But there are so many craft beers now, who has the time?
6. Squash and racquetball.
7. Fixing up an old car. Maybe because no one knows how to anymore?
8. Astronomy. Meaning you own a telescope and actually use it on a regular basis.
10. Toy collecting. The whole Beanie Babies fad was 20 years ago.