Ask YC: focus / knowing what to stop working on ?

I love creating new things. Here's a list of some things I've worked on lately:

Leenooks.com which is backed by an open source wiki I created, DedaWiki

Linuxsi.com - hack to showcase linux friendly stores in Italy.

Hecl (hecl.org), which is getting lots of stuff for Android.

Langpop.com - programming language stats

SqueezedBooks.com - business book summaries

All in addition to paid work for clients.

How do other people deal with staying focused, and dealing with past efforts? Something like Linuxsi.com or Leenooks.com is a nice idea and people find it valuable, but it's not startup material, and it takes up a bit of time to run them. I don't like the idea of getting rid of things like that, but maybe it would be the best, so I could focus on things like Hecl. How do other people deal with offloading the less important things in order to concentrate and focus?

I think having a cofounder and working on something full time, 'for real' would definitely be one step, but unfortunately I don't have that right now.