I made my own CMS just for this, to collect stuff in one place and then maybe use that elsewhere. At first I did RSS -> third party sites -> Twitter and Facebook, but I got tired of that after a while (I'm not really using either, so why spam stuff there), but just knowing that I
could do that is kinda comforting. For now the only "syndication" I do is to output nodes text/images in JSON to make mashups that automatically grow as I add and tag content in the "repository", or to output links to mp3 files as playlist for a flash audioplayer, etc.
I initially planned to open source it, but then I decided I'd rather just do my own thing without having to worry how it works for others, and especially how they would upgrade it when a new version comes out. But I recommend it wholeheartedly. Make your own CMS and have it do exactly what you need it to do, with all the metadata you could possibly want!
For example, recently I added the ability to add a date to nodes, as exact or rough as I want (millenium, century, decade etc up to specific days... I don't even have a use for that currently haha, I just wanted to have it). I don't just have tags, I have several taxonomies, some just visible to myself, nodes are nested in two ways (imagine every comment here could also have a "subtree" of comments, ad infinitum), and I could even use it to make something forum-like if I wanted to, since each node has settings for who may attach what to them, and who may attach what to those nodes in turn, several levels deep. It was a lot of work, and the code sure is ugly, but so far I have seen nothing out there that even tempts me to switch. Nothing fits me as well as the glove I made for myself :)