I found this really cool text, and would like to use the style but for a different word. How can I do it in GIMP or pixlr.com?
My suggestion is to find a similar font on dafont.com > Comic Fonts or Blambot > Fonts. There are fonts out there where that style is already applied to the letters. In the case of the latter, the comic book fonts are sorted by purpose; you can find blocky overlapping letters under "sound effects" fonts.
Either way: Why re-invent the wheel, right? :)