Progwhiz Hex editor offers all the features of powerful desktop editors and more:

Features

Text Search/Replace
Hex Search/Replace
Text wildcard Search & Replace
e.g. HEL? would find all words that begin with "HEL"
e.g. HE?P would find all words that begin with "HE" and end with P.

Hex Pattern Wildcard Search & Replace
e.g. 55??AA would find all Hex patterns that start with 55
then an unknown hex value followed by AA
e.g. 55??AA??BB would find all Hex patterns that start with 55 then an unknown hex value followed by AA, then an unknown hex value followed by BB

-==NEW==-
** The Hex wildcard now supports 4Bit hence two(2) '??' is required to represent one 8Bit hex unknown **

To get the full version please goto :

http://m.slideme.org/application/progwhiz-hex-editor

Screenshots: 

Video: