I cater to the idea you should keep things simple and fast to load so don't flood your post with images; while it is true that images can help attract the reader to many will have the opposite effect.

 things you must have on your blog:
  - retweet and share on facebook buttons and if you really serious add a few others to..
 - a comment system, though many blog services offers good built in ones I would sugest trying a third party like disqus, intensedebate, or backtype (also you should use backtype to gather your own comments across the web). Why do this? Because it could help you broaden your reach because people who use these services get their comments in one place... More traffic
- use friendfeed to gather all your feed into one feed it makes it easier for people to follow you on the web, another option is flavors.me
- if you write a review or mention products you could concider including amazon links for revenue.
- tweet your postings

Should you add addons/apps?
I subscribe to the idea of a clean and simple blog, and would in general say no. It's a matter of taste really and if you do want apps then try and customize them as much as you can to integrate them neatly into your design... Ask yourself what the app will add to your blog... Keep in mind they might slow down your load time.

{This entery was jotted down on my nokia n97 and will be polished and spelled checked thurly at a later stage, just so you know..}