  We study through integral equation theory and numerical simulations the
structure and dynamics of fluids composed of ultrasoft, nearly Gaussian
particles. Namely, we explore the fluid phase diagram of a model in which
particles interact via the generalized exponential potential u(r)=\epsilon
exp[-(r/\sigma)^n], with a softness exponent n slightly larger than 2. In
addition to the well-known anomaly associated to reentrant melting, the
structure and dynamics of the fluid display two additional anomalies, which are
visible in the isothermal variation of the structure factor and diffusivity.
These features are correlated to the appearance of dimers in the fluid phase
and to the subsequent modification of the cluster structure upon compression.
We corroborate these results through an analysis of the local minima of the
potential energy surface, in which clusters appear as much tighter
conglomerates of particles. We find that reentrant melting and clustering
coexist for softness exponents ranging from 2^+ up to values relevant for the
description of amphiphilic dendrimers, i.e., n=3.
