This describes how to add a keyword bookmark (Example is Firefox) to search for a contact in CiviCRM. The need for this came from answering incoming calls from clients - the ability to quickly bring up a list of possible matches helps leverage client details while on the phone.
The resultant url was:
: The URL for your CiviCRM install.
%s: This is where Firefox will insert the search terms - 'smith' in the example below. Adjust for other browsers or methods of invoking, e.g. Launchy , Quicksilver or IE Accelerators.
Thus with this keyword bookmark enabled (I used 'civi' as the keyword) I can type 'civi smith' in the address bar and a page will come up listing all 'smiths' in my database.
Taking it further.
In the URL above, the first link is the original link from the first example, while the second is the address used if no search terms are given.
I believe this can work for other custom searches as well, you need to adjust the CSID accordingly and (in my unlearned case) add a sprinkling of trial and error.