I noticed a logo tattooed on a Blackgate thug's foot in a Batman: Arkham Asylum (PC) predator challenge. Does it signify some organization in the DC universe, or is it something else entirely? I was thinking the League of Assassins, but I can't find a logo for that, and this fellow seemed entirely too inept to qualify.
As per Paul's comment above, the symbol on the character's foot appears to be a stylised version of the Sheikah Symbol repeatedly used in the Zelda game series.
Adding weight to this theory is an interview given by Sefton Hill (Game Director for "Batman : Arkham Asylum") in which he describes his key influences as being Metroid and Zelda.
There are some influences from other games in Batman: Arkham Asylum. You said you didn't necessarily look to other Batman titles, which was probably a good idea for the most part. But can you comment on the specific influences? I see a little bit of BioShock, and a little bit of Eternal Darkness. Can you comment on any of the game influences that you have had in design?
SH: Like the rest of the design world, I'm a big fan of Zelda and Metroid games, going back for years. They were definitely big influences. I like that sort of approach to design -- giving you a number of different gadgets and abilities that you can use and combine in different ways, and the way that combines and the feeling of being in this complete other world. Those games were definitely a big influence. I played Eternal Darkness and I really liked that. Those guys did a great job with that. They had a sanity system in there that freaked a lot of people out. It was a nice idea.