SeaMonkey Portable is still creating directories in C:\Documents and Settings\username\Application Data\ and C:\Documents and Settings\username\Local Settings\Application Data\ everytime it is launched...this is not a portable app, despite the splash screen. This could get unknowing users in a lot of trouble if they are running this at work...
This is by design and only while the application is running. On exit, they are removed. Firefox Portable does the same thing.
If someone is not permitted to run these at work, then they absolutely should not. Nothing you run from a flash drive is stealth. Everything leaves traces that you can not delete unless you are an admin on the PC you are running on (which you are not at work). Anyone who tells you otherwise is either mistaken or lying.
Sometimes, the impossible can become possible, if you're awesome!