I've earlier complained that signatures weren't allowed long enough, since slashcode automatically adds in tags to any link you enter, etc.
Whoever(TM) at Snop.com wrote a userscript that takes care of this. You can hardcode your signature (or a list of signatures) into Slashdot Random Sig and it will randomly pit from the sigs you entered.
Nice, since it adds the sig the the text box when you submit, making it body text. This means your sig displays even if people disable sigs, but more importantly allows for longer sigs.