On special occasions, Ceefax used to have commemorative/decorative pixel art pages.
This very purple page is from Ceefax's Wimbledon coverage. Compare to the digital teletext version and it looks very low tech. Snazzy, though.
Graphs aren't used much on teletext any more but this page from Oracle in the 1980s is a diagram for motorway delays. Inventive if basic manipulation of the format.
An old Fun and Games page. Now defunct, this used to be the most fun part of teletext, containing tacky quizzes and puzzles that could be completed in a commercial break. Nice little image of a lighthouse but I don't know the relevance of it.
Source: Teletext Then and Now