Here's a set of pages where students place numbers in the appropriate space on the number line.
Here's a set of train-themed number line poster cards from 0-20.
Here's a number line generator that allows you to select the interval, annotation interval, number of tick marks, and start number, as well as the number of number lines per page.
Here's a great post on using a shoestring (literally) to help students understand number lines.
Here's a set of posters designed to be displayed as a number line in the classroom. Includes the numbers 1-30 which appear in two rows.
Here's a set of posters from 1-30 designed to be displayed as a classroom number line. Includes the numeral, number word, and ten frame representation.
Here's a set of number lines to 10 and 20, alphabet strips (lowercase and uppercase), and a picture strip to teach students how to use a number line/alphabet strip and identify ordinal numbers.
Here's a number line from 1-0 with a pirate theme. Each Number is depicted on the sail of a pirate ship and pictured around the ship are quantities of sharks, birds, clouds, pirates, waves and cannons that match that number.
Here's a page with several different number lines from 0-10. Includes some editable resources.