I noticed that in my JBoss Application Server 7 installation under standalone/tmp
I have 400 MB of files related to past deployments, some of them a few months
I do not have experience with version 7 of JBoss but with 5 I often had issues when redeploying apps which went away when I cleaned the work and tmp folder. I wrote a script for that which was executed everytime the server shut down. Maybe executing it before startup is better considering abnormal shutdowns (which weren't uncommon with Jboss 5 :))