Today I came across a neat plugin for Eclipse, http://www.richinternet.de/blog/index.cfm?entry=1758AACF-910C-DE52-368E1421BEFDA19B
It will automatically switch perspectives when you open a file of a certain type associated with that perspective. That's convenient for me, as I use three perspectives generally and some have icons at the top bar that others don't that I need. I don't know if something like this has already been created for Eclipse, but I find it very convenient!
Sadly it isn't a plugin that you can install via the Install New Software menu, but it is simple to install nonetheless. I suggest that you restart Eclipse after putting the JAR into dropins (if you had it open when doing so), then set file associations, then restart again. That made it work for me perfectly.