This page allows you to set the labels used on the X and Y axes. It also allows you to choose the font, style, size and colour used, as well as how far to position from the axis, which axis to attach to and whether to include any units (as a string in parenthesis). The text shown is an accurate rendering of what is shown in the plot window.
As with the title you can insert any characters from the font, and use AST Escape sequences to get effects like super and sub-scripting.
SPLAT-VO -- A VO-enabled Spectral Analysis Tool