A plug of my tools:

To visualize data coming in from a pipe, can pipe it to

https://github.com/dkogan/feedgnuplot

Very useful in conjunction with other tools to provide filtering and manipulation. For instance (the first one is mine):

https://github.com/dkogan/vnlog

https://www.gnu.org/software/datamash/

https://csvkit.readthedocs.io/

https://github.com/johnkerl/miller

https://github.com/eBay/tsv-utils-dlang

http://harelba.github.io/q/

https://github.com/BatchLabs/charlatan

https://github.com/dinedal/textql

https://github.com/BurntSushi/xsv

https://github.com/dbohdan/sqawk

https://stedolan.github.io/jq/

https://github.com/benbernard/RecordStream