  We present an isochrone server for semi-empirical pre-main-sequence model
isochrones in the following systems: Johnson-Cousins, Sloan Digital Sky Survey,
Two-Micron All-Sky Survey, Isaac Newton Telescope (INT) Wide-Field Camera, and
INT Photometric H$\alpha$ Survey (IPHAS)/UV-Excess Survey (UVEX). The server
can be accessed via the Cluster Collaboration webpage
{http://www.astro.ex.ac.uk/people/timn/isochrones/}. To achieve this we have
used the observed colours of member stars in young clusters with
well-established age, distance and reddening to create fiducial loci in the
colour-magnitude diagram. These empirical sequences have been used to quantify
the discrepancy between the models and data arising from uncertainties in both
the interior and atmospheric models, resulting in tables of semi-empirical
bolometric corrections (BCs) in the various photometric systems. The model
isochrones made available through the server are based on existing stellar
interior models coupled with our newly derived semi-empirical BCs.
  As part of this analysis we also present new cluster parameters for both the
Pleiades and Praesepe, yielding ages of $135^{+20}_{-11}$ and
$665^{+14}_{-7}\,\rm{Myr}$ as well as distances of $132 \pm 2$ and $184 \pm
2\,\rm{pc}$ respectively (statistical uncertainty only).
