Useful links to JQuery grids utilizing (mostly) standard UI themes and/or very little code.
Google!
http://jquery-ui.googlecode.com/svn/branches/labs/grid/tests/static/grid/default.html
Datatables.Net:
http://www.datatables.net/styling/themes/smoothness
Ke-Cai:
http://www.ke-cai.net/2010/01/theme-your-table-with-jquery-ui.html
Trirand:
http://www.trirand.com/blog/jqgrid/jqgrid.html
Stackoverflow:
http://stackoverflow.com/questions/2613632/jquery-ui-themes-and-html-tables