Where should I install my program

[OOzy Pal]

Where should I install my programs that are not packaged. For example,
I have  program that I downloaded and after extraction (untar), I can
run it as

java -jar xyz.jar

Where should put it I searched the net and found most people prefer

/usr/local

should I make mine as?

/usr/local/xyz

or should I go inside one of the existing directories?

-- 
OOzy
Kubuntu-Edgy