It starts with a trick I picked up from the main posterous blog. You can target a specific tag in the posterous RSS feed by appending “tag=” to the address
This lets me target the specific sections to be displayed on my site in specific columns.
My site is essentially a vb.net RSS parser, targeted at my three blog categories (Lifeblog/Geekblog/About me), writing the output from these into each section of the page. A little HTML/CSS re-writing is required to ensure that images aren’t too wide, and that videos don’t overflow.
On the posterous site itself I found an excellent skin site at http://themes.posterous.com/ which offers some great implementations. The one I selected (with a few tweaks) allows you to put your tags as tabs at the top of the page, letting me merge three posterous sites into one.
Blogosphere – I hope that helps !