QBE - Query By Example is an awesome feature for ADF 11g tables and a number of times can eliminate the need of a search panel completely if you are limited to search the data based on a particular column values.
I am not saying anything new here but just highlighting this feature. So, also does not make sense to copy paste from dev guide etc. All the supported operators are well documented at http://docs.oracle.com/cd/E23943_01/web.1111/e16272/databound_forms.htm#ADFJE389
For those who want to change the QBE behavior for more advance requirements then there is a way to do that well. There is an excellent whitepaper on that and can be followed at https://docs.google.com/viewer?url=http%3A%2F%2Fwww.oracle.com%2Ftechnetwork%2Fdeveloper-tools%2Fadf%2Flearnmore%2F30-table-filter-queries-169172.pdf