Network map does tell you if a certain Virtual Server is referencing iRules,
but I'm afraid that application-specific parsing of your iRule code will need to be done manually as iRules are customer-created scripts, and since iRule purpose might greatly vary from one script to another those can't be "standardized" into other configuration objects for parsing.
I was thinking that maybe iHealth tool might help you with that ... I recall that "browsing" LTM-specific objects like a VS will return the full configuration of all profiles, rules, pools etc. that are linked to that object .. I'd say it might be worth giving it a try.
Also from iHealth you can still access all configuration files, including bigip.conf which does contain LTM iRules.