  We give a complete description of the horofunction boundary of
finite-dimensional $\ell_p$ spaces for $1\leq p\leq \infty$. We also study the
variation norm on $\mathbb{R}^{\mathcal{N}}$, $\mathcal{N}=\{1,...,N\}$, and
the corresponding horofunction boundary. As a consequence, we describe the
horofunctions for Hilbert's projective metric on the interior of the standard
cone $\mathbb{R}^{\mathcal{N}}_{+}$ of $\mathbb{R}^{\mathcal{N}}$.
