Today Tchibo announced the introduction of a dayflat for € 2.95 (billed by calendar days and throttled after 1 GB). That's € 0.45 more expensive than Fonic, who also use the O2 network, but all in all Tchibo now offers the most attractive combination of data tariffs in a single SIM.
Details are already available at
Germany - Tchibo - Prepaid Wireless Internet Access