While jailbreaking or softmodding is a debatable act. I am not sure if the forum permits posts on it. If they are not allowed, will request mods for pardon and have this post deleted.
To me it is just changing software on a device I paid money for, so in that sense, here goes the best tool I have used to softmod my device
Just download the tool, have 2 SD cards handy (SD and not SDHC are preferable). If you have one 1 GB SD card that should also suffice.
modmii - ModMii - Google Project Hosting