Back in the day, we would scroll slowly and carefully through the microfilm on the microfilm reader.
Until today, users could browse Ancestry.com's collections by specific locality (state, county and township for the census) by clicking on the state at the bottom of the web page for the specific database. I doubt that I ever used that feature because it was at the bottom of the page.
Now, Ancestry.com has made it a lot easier for us to browse through records for a specific locality (e.g., state, county and township - and Enumeration District in cities - in census records). Anne Mitchell wrote her post Improved Data Collection Search Pages to describe what they have done to help researchers browse through the census pages.
In fact, Ancestry.com says they have added this feature to all of their databases. I checked several other databases and the new "Browse This Collection" feature is there.
Here is my look at the process, with a nice little surprise at the end. From my home page, I like to click on the specific year of the census (note that I have customized my home page so that the Census Records are right up at the top of the page):
I wanted to browse through Killingly, Windham County, Connecticut, so I chose "Killingly" from the list and the first Page of the census for Killingly came up:
I can navigate this census for Killingly by clicking on the small left and right arrows on the right of the header, just above the actual census record, and to the right of the "Go" link. If I wanted to jump to a certain page, I could click in the field for the page number, type in a page number and click on the "Go" link.