By far the most common type are the 'articulated club' type of flails like what the hussites used, which you can also see in that Myarmoury thread, an infantry weapon which usually only had a couple of links and were typically made of a long wooden handle (four feet or more) with a fairly long club-like striking surface (also wooden but with iron bands, spikes, and / or knobs). This as far as i know is the only type which saw widespread military use, notably by the Hussites but throughout Central Europe. I have records of town armories buying them en-mass.
But the ball and chain type did also exist, sometimes with very long chains (sometimes called a 'meteor hammer') you see them in auction sites and so on.
"In the case of an ailing social order, the absence of an adequate diagnosis... is a crucial, perhaps decisive part of the disease." -Zygmunt Bauman
"With any luck we'll be in Stalingrad by winter. " - Anyonymous German soldier