[development] modifying the output of blocks

Hello all, Is there a way I can alter the output of other modules' blocks from my own module? This would be similar to the nodeapi hook on $op = "view" If this doesn't work, then I would like to at least detect weather a block has been rendered on the current page to decide weather to emit javascript related to that block. Otherwise I would have to add the javascript on all pages needlessly. Thanks! -- Ashraf Amayreh CEO | O-Minds Cell. 962 78 8099997 Tel. 962 6 5655150 Fax. 962 6 5675150 Skype: aamayreh www.o-minds.com web development | web design user experience | branding design Connect with us on Twitter http://twitter.com/ominds Connect with us on LinkedIn http://www.linkedin.com/in/aamayreh