Using Mozilla in testing and debugging web sites (via MozillaNews). Heck, Netscape 4.0 was better than any given version of Internet Explorer for debugging HTML and Javascript. Perhaps it’s because Microsoft comes from a culture which sharply divides users from developers (so to debug a Javascript error, IE launches a full-featured IDE), while Netscape developers (who also target UNIX users) knew way back that the distance between user and developer is as small as clicking view source…
Actually, the few debugging tools microsoft does provide – view source using the unsatisfactory notepad, and it’s annoying (to users), confusing and unhelpful (to developers) javascript error message boxes – create more problems than they help solve.