I thought I'd ask, it's interesting.
Mine off the top of my head - I thought of a boy I met as a young teenager. I couldn't remember his surname, only his first name. The day later, he appeared on my suggested friends for Facebook. No mutual friends etc. We met in Tunisia. I hadn't searched for him either. Last time I saw him was about 10 years ago.
I always had a gut feeling my dad would 'appear' into my life when I became an adult. I just always imagined it from as young as 8. He messaged me on my 18th birthday. Hadn't seen him since before I learned to walk.
Last one, my mum's good friend moved to Cornwall when I was little. I thought of her before going down there for sma weekend recently. It turns out that the person I hired wetsuits from was her husband. We took a photo together out for lunch. My mum said she almost choked as she thought she'd fallen off the face of the earth.