This really should be in the "beginners section" as I'm sure open limping at stakes higher than $25NL is a recipe for dissaster.

At a loose table I will open limp anything that I would normally play except 99/TT+ (AK/AQ/88/99 are about 50/50 between raising and limping). That means suited connectors, low pp, any two cards J or higher (QJ+). I'll do this in early position and sometimes to mid-position.