In Web 1.0 there were a number of browser-based website creation platforms - e.g. Geocities, Angelfire, Tripod, Homestead and Brinkster (I myself used nearly all of those, back in the day). These apps were very popular in the mid to late 90's, because they made web publishing relatively easy. The most successful one, Geocities, was eventually acquired by Yahoo! in 1999. In the Web 2.0 era, aka the social web, blogging platforms such as blogger.com, LiveJournal, TypePad and Wordpress.com have largely taken over. Not to mention social networks like MySpace and Facebook. However the 'read/write web' has expanded the market for web publishing exponentially, so there is still an active market for traditional website building platforms.
Market Players
Geocities itself is still active in the website creation market. Here are some of its competitors:
Google Sites (it evolved out of one of Google's acquisitions, JotSpot, and is now available for free separately from Google Apps)