Listing and sizing your objects:

To list your objects, you have several options

• objects(pattern="track") # equivalent to UNIX "ls *track*"
• objects() # lists all objects
• ls() # lists all objects
• lsf.str() # lists all functions with their arguments
• ls("package.fields") # lists all objects in the fields library

Removing objects whose names follow a pattern

• remove(objects(pattern="track")) #remove particular objects

Determining object size

• >object.size(my.object)
• use the format.bytes() function to write out the size in more readable format 
  >format.bytes(object.size(my.object))
• use the ls.sizes() function to find the largest N objects 
  >ls.sizes(top=15) # returns the largest 15

Thanks to Fang Chen for most of these tips.