When I went to France last summer I accessed the web with an Orange Mobicarte (prepaid SIM sold for < € 10 at eBay.fr). After activating the tariff option "Internet Max" (€ 9/month) you officially get a data volume of 500MB for the web + 10 MB for eMail (SMTP, POP3, IMAP), both for handset-based use only. But actually, as I expected due to reports on German forums, access was neither limited to handset-usage, nor did the cap of 500MB apply. Only the 10MB-limit for eMail seemed to be enforced. Even HSDPA and EDGE were available and provided decent data rates. So that's an interesting offer if you don't generate much traffic.
More info at
France - Orange - Prepaid Wireless Internet Access