I've spent some time integrating Gallery into my website, with the goal of making it look seamless to the rest of the site.
http://gallery.waun.net
Here are the changes that I have to make when I install a new version. Everything else is accomplished by manipulating the html_wrap directory. Notice that I do not use the top-level gallery page, ever. The image frame is a custom job.
To upgrade to newer gallery version:
1. Extract new gallery on top of old one
2. Copy ./html_wrap directory (if necessary)
3. Configure the following non-default options: (if necessary)
$GALLERY_EMBEDDED_INSIDE="true"
$GALLERY_EMBEDDED_INSIDE_TYPE="custom"
4. Make the following changes:
./init.php
+ Copy the "Standalone" section to the embedded switch/case as 'custom'
./view_album.php
+ Make logout appear
+ Remove Album: Prefix
+ Change "modcaption" to 100% width
./layout/navigator.inc
+ Make navigator always appear
+ Make prev/next table elements tighter
./layout/adminbox.inc
+ Remove admin["text"]
./layout/breadcrumb.inc
+ Remove & and Add <BR> after each breadcrumb element