%%commentbox
__see also__\\
[http://www.jspwiki.org/wiki/FAQFormatting]
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This

{{{
%%(text-align:center)
!This text is centered.
%%
}}}

produces this

%%(text-align:center)
!This text is centered.
%%


You can center tables too:
{{{
%%center
|This|is|my|table
%%
}}}

produces this 

%%center
|This|is|my|table
|This|is|my|table
%%