Turn Spotlight into an application launcher only
You can easily turn Spotlight into only an application launcher by adjusting the Spotlight search settings.
* Launch System Preferences
* Click the Spotlight icon
* Uncheck every item except for “Applications” and “System Preferences”
* Close System Preferences
Now your Spotlight menu will only return Application and System Preference results when a search is made, making for a very quick and completely integrated application launcher. Of course, you can use Spotlight as an application launcher even with the other search category items selected, but your search results will be a bit more cluttered.

I prefer leaving spotlight indexing everything and use Berokyo (http://www.berokyo.com) from Think, Code, Release to quickly access and launch my applications.
[...] use Spotlight constantly to find literally anything on my Mac or iPhone, it makes for an incredible application launcher and with all the search operators you can dig really deep into your file system and find just about [...]
[...] use the Dock as an app launcher, this probably won’t be that useful for you. I almost always use Spotlight to launch apps and have my Dock automatically hide, so I’m going to try this out for a while and see how [...]