Is there a way to manage startup programs to help find conflicts?

As far as I know the easiest, possibly the only way, to stopping normal programs launching is via System Preferences : Accounts and then go to the Login Items tab. Just remove the applications from there. That won't uninstall the application, just stop it from loading on startup.

So just what did you have in mind?

I'm trying to find a way to easily enable/disable the startup programs.

I don't really want to remove and reinstall startup programs using the controls in System Preferences.

That includes enable/disable login items?

Some programs aren't in login items but do get added to launchd, some programs like TechTool Pro have their own method and run in the background.

There is no central place to look at a list of all the startup items; or all the launch services and background tasks (shame, too).

Use to be there was a Startupitems in System/Library but no more, or not used as much. Things can be in folder locations, or from where they are installed. What you want is like the old "Extension Manager" which doesn't exist.

You might look and see features and tools in SL Cache Cleaner
http://www.northernsoftworks.com/snowleopardcachecleaner.html

Careful, I would not run a cache cleaner without a good backup at hand*:

http://www.macmaps.com/backup.html

- * Links to my pages may give me compensation.

The hatter wrote:
Use to be there was a Startupitems in System/Library but no more, or not used as much.

There is both a /System/Library/StartupItems & /Library/StartupItems folder. Both are empty by default, so anything in them has been put there by a third party application installer. This is not uncommon for certain kinds of system add-ons.

Regarding what Print It! may have installed, look for that info in its documentation or for an appropriately named installer log item using the Console app.

Good gracious, it is NOT just a "cache cleaner" as I alluded, it has a LOT of other features in there, did I say clean the caches? NO. I said look for something to manage what OS X launchd is up to.

Don't jump to wrong assumptions. Or knee jerk reaction.

That's a little backwards. It is most likely that something installed by the Print It! installer or app is interfering with a normal boot. Check its documentation or the logs for clues about what it installs.

True,
But that's one facility within that tool which if used indiscriminately can cause more problems than it is worth. This is why I have to caution against it.