Wajig

I discovered this tool about a year ago and i fell in love with it. At start i used it to hold packages that i didnt want to get updated with others when i update system but later it became handy in other tasks as well. You can install wajig on ubuntu 9.04 by:
apt-get install wajig
OR
aptitude install wajig

and to just have an idea of what wajig is cable of check this.