Looking at your, er, colorful listing, it is going to be difficult to get your sight to blend with anyone else's sight.

Your choices seem to be, a) provide the entire page (i.e., all the HTML), b) provide the content of the listing and let them suck it up (via LWP::Simple, e.g.) and format it themselves.

I suspect that the programming capabilities on the receiving end are varied, and insufficient.

You could just provide the whole page, but via query parms allow for different style sheets to be pulled in. If you want to maintain profile information, you could do all manner page customiziation on your end, such as custom logos, etc.