http://www.uselesspickles.com/triangles/
(That page was published in something like 2006... "Nothing new under the sun" indeed.)
uparrow =
data:image/gif;base64,R0lGODlhCgAKALMJANPT06 enp%2Fb29r%2B%2Fv52dnfn5%2Bbq6usLCwpqamv%2F% 2F%2FwAAAAAAAAAAAAAAAAAAAAAAACH5BAEAAAkALAAA AAAKAAoAAAQcMMlJq712GIzQDV1QFV0nUETZTYDaAdIhz3ISAQA7
Same thing demonstrated in 2008 - http://www.howtocreate.co.uk/tutorials/css/slopes
And more polygons by Tantek Çelik in 2001 - http://tantek.com/CSS/Examples/polygons.html
The speech bubble effect in the demo can also be done without presentational markup by using pseudo-elements - http://nicolasgallagher.com/pure-css-speech-bubbles/
Check out the 'Twitter' and 'Email' ribbons on http://imeveryone.com/about
ah someone already posted it :)
http://www.uselesspickles.com/triangles/
(That page was published in something like 2006... "Nothing new under the sun" indeed.)