Get all loaded data.frames

Which data.frames have we loaded?
ls()[ lapply( lapply(ls(), function(x) gettextf("class(%s)", x)), function(x) eval(parse(text=x))) == "data.frame" ]

All available functions in a package:
ls.str(pos = 1, mode = "function")

All installed packages:
search()
(.packages())
(installed.packages())

All available function on search() path:
strsplit( lsf.str(pos = length(search())), " :")