Via Freedom To Tinker, the world's smallest P2P application, happily republished because its under Creative Commons also:
# tinyp2p.py 1.0 (documentation at http://freedom-to-tinker.com/tinyp2p.html)
import sys, os, SimpleXMLRPCServer, xmlrpclib, re, hmac # (C) 2004, E.W. Felten
ar,pw,res = (sys.argv,lambda u:hmac.new(sys.argv[1],u).hexdigest(),re.search)
pxy,xs = (xmlrpclib.ServerProxy,SimpleXMLRPCServer.SimpleXMLRPCServer)
def ls(p=""):return filter(lambda n:(p=="")or res(p,n),os.listdir(os.getcwd()))
if ar[2]!="client": # license: http://creativecommons.org/licenses/by-nc-sa/2.0
myU,prs,srv = ("http://"+ar[3]+":"+ar[4], ar[5:],lambda x:x.serve_forever())
def pr(x=[]): return ([(y in prs) or prs.append(y) for y in x] or 1) and prs
def c(n): return ((lambda f: (f.read(), f.close()))(file(n)))[0]
f=lambda p,n,a:(p==pw(myU))and(((n==0)and pr(a))or((n==1)and [ls(a)])or c(a))
def aug(u): return ((u==myU) and pr()) or pr(pxy(u).f(pw(u),0,pr([myU])))
pr() and [aug(s) for s in aug(pr()[0])]
(lambda sv:sv.register_function(f,"f") or srv(sv))(xs((ar[3],int(ar[4]))))
for url in pxy(ar[3]).f(pw(ar[3]),0,[]):
for fn in filter(lambda n:not n in ls(), (pxy(url).f(pw(url),1,ar[4]))[0]):
(lambda fi:fi.write(pxy(url).f(pw(url),2,fn)) or fi.close())(file(fn,"wc"))
Its been my intention to learn more Python these past couple of months, perhaps this will provide the inspiration to finally write that Craigslist search term notifier app (Python based) I've been meaning to start...
