Maximum Flow with Binary Capacities
According to Goldberg's post on the Fortnow–Gasarch blog from 2012, the best algorithm for unit capacity networks is the Karzaon/Dinic/Even–Tarjan algorithm, which runs in time $O(\min(n^{2/3},m^{1/2})m)$ time. The post came after Orlin's $O(nm)$ algorithm. Goldberg and Rao extended this result to any constant capacity (their running time is linear in the logarithm of the maximal capacity).

There is a more recent line of work which gives an approximation to the maximum flow in time $O(m^{1+o(1)})$, but this doesn't make use of any bound on the capacities.