TextAutocomplete collects "words" in the current buffer and those that you type and offers you automatically a list of possible completions as you type a new word. It's pretty similar to the jEdit's function "Complete Word" but it's automatic, you don't need to press any key to invoke the list of completions. The plugin was inspired by a similar functionality in OpenOffice.org.

The plugin is configurable, you can define what a "word" is, what words (not) to remember etc. - see the docs. It's also possible to modify manually the list of remembered words.

You have to start the autocompletion for every buffer where you want it.