[aeyes]

ICQ had a powerful global search, you could search by nickname, real name, country, city, date of birth and so on.

Back in the day nicknames were still pretty unique.

[op03]

Also had a search by interest feature if I remember right.

There were no programming classes back then at my school and I found someone, half way across the world, who patiently taught me programming everyday.

[rasz]

IT was great for dating around 2000. Search by gender, age, city, open conversation and try my luck. Ended up in ~4 year long relationship from random contacts.