Simple RSS to HTML converter
The small improvement I would like to suggest you is related to performance in terms of speed.

In flatten_unicode_keys(dic), you use for key in dic.keys(): which is less fast than for key in dic:. This is mentioned in PEP 234:


  
  Dictionaries implement a tp_iter slot that returns an efficient
  iterator that iterates over the keys of the dictionary. [...] This 
  means that we can write

for k in dict: ...

  
  which is equivalent to, but much faster than

for k in dict.keys(): ...

  


An other side note: it is a better coding habit not to encode the container type into the name. So instead, for example, of typing dic, use a name which actually better describes what that dictionary consists of.