With all due respect to the anti-task killer crowd (I'm anti-task killer too), I have to agree 100% with the OP that some apps make themselves at home on android and it can be annoying.
Slacker, for example, plays music. I don't need it running in the background 24x7, contacting home, downloading songs, etc., etc. Just play the music when I want, then go away. Pandora manages to do this and Slacker doesn't. I uninstalled Slacker.
I know, sometimes, like in the case of an email client, there's a completely legitimate reason for running on boot. That's understandable, but other times it comes down to control of my phone. It's about knowing what's phoning home and what's killing my battery (even just a little). I want control over my phone and I'm picky about what runs. I tolerate stock apps that run on boot, but I will not tolerate it in software I install myself. When dolphin (a browser) updated a few months ago, it ran on boot. There's no reason for my browser to do that. I uninstalled and complained to the dev. The problem was rectified with the next update. If it bothers you (and maybe it should, at least a little) then complain to devs via email and in the market comments.
What else besides complaining?
- Just root it.
- Just uninstall it.
- Use the autostarts app.