A few I've found myself:
HTTPie instead of cURL
http PUT example.org name=John
[email protected]
https://github.com/jkbr/httpie
ffind instead of find
ffind --type=f make-?dist\.sh$
https://github.com/sjl/friendly-find Still in prototype phase
dstat instead of netstat/iostat/vmstat/etc
Dstat's output by default is designed for being interpreted by humans in real-time
https ://github.com/dagwieers/dstat
Silver Searcher better than Ack better than Grep
It searches through code about 3x-5x faster than Ack.
https ://github.com/ggreer/the_silver_searcher