ICA, as has already been pointed out, stands for "Industria, Comercio y Avisos", and the full name of this tax is "Impuesto de Industria, Comercio, Avisos y Tableros", as shown in the site already cited by Benjamin and Marta: http://www.shd.gov.co/portal/page/portal/portal_internetold/... .
As explained here, it is a direct municipal tax on industrial, commercial and service activities in the District of Bogotá.

The "avisos y tableros" part is not explained in this site, and its history is curious:
"el impuesto de avisos y tableros fue creado por la Ley 97 de 1913 (Art. 1, literal k) para Bogotá siendo el hecho imponible ‘la colocación de avisos en la vía pública, coches, tranvías, estaciones de ferrocarriles, cafés y cualquier establecimiento público’ tributo que se hizo extensivo a los municipios mediante la Ley 84 de 1915."
This was amalgamated with the Impuesto de Industria y Comercio in 1983.
http://actualicese.com/actualidad/2007/09/17/kpmg-implementa...

So really, to be accurate we should call it something like "municipal tax on industrial and commercial activities and signage", but I think the common formula "municipal business tax" covers it adequately.

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Note added at 7 hrs (2011-09-29 21:41:32 GMT)
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An equally valid alternative, in my opinion, would be "local business tax". I think "municipal" or "local", though not part of the Spanish name, should be included to make it clear to the uninitiated what sort of tax this is.