A simple plugin which adds the Sort Lines function to the Edit menu.
Sort is applied on selected lines if any, on the whole file otherwise. Sort is case-insensitive and ascending, no custom configuration is planned for now.
NB: another plugin is available to sort property files (with smarter sort): Property Sorter.
Web site: http://idea-linessorter.googlecode.com
Plugin page: http://plugins.intellij.net/plugin/?idea&id=5919