I use this to extract and later calculate the difference between two times.

URL validation with http/https

This will parse the fields portion of a mysqldump lines such as: INSERT INTO users VALUES (42,'Bob',12.34,NULL,'It\'s ok!');

get the file extension of a given filename

Regex For finding username:password

Detects valid Roman numerals (up to 3999), and splits into 4 capture groups: thousands, hundreds, tens, and units.

if you use the service you may want to know a state of some responses

Detect and cut lines containing variables.

bits and pieces of reusable replacements in CSS @font-face rules

The file name validation algorithm from MS KB905231, I assumed the prohibited suffixes included the file extension. I.e. 'foo.doc.files' would not match but 'foo.files.doc' would.

date should be in format YYYYMMDDHHMMSS

Identifies two groups, each group using a regex, then replaces group 2 with group 1.

Extract port from URL

Letras, Ñ, acentos, números, guión y barra baja