Recently, Aldi supermarkets in Germany have started selling unlocked 3G USB dongles for €59. Yes, unlocked, which means that the buyer is free to either use them with a SIM card that can also be bought in the supermarket or with a SIM card of a different operator. For the details see here (while the link leads somewhere).
The SIM card offered by Aldi is for the German E-Plus network, which unfortunately is quite patchy and not upgraded to HSPA yet. I wonder if it might be the last non-HSPA 3G network left in Europe!? Prices for daily use are €1.99 with a traffic limit of 1 GB or €15 for 30 days with a traffic limit of 5 GB. Stunning prices but don't ask for high speeds.
I am glad to finally see this happening in Germany, after it has pretty much become common practice in Austria for a year or two now already. To my knowledge, Germany is only the second country so far where unlocked 3G dongles can be bought in supermarkets. If you are aware of any other countries except Austria, please let me know.
Let's hope that similarly as in Austria this move will stimulate competition around pre-paid offers where the SIM card for Internet access can be bought independently from the 3G dongle. After all, I feel a bit silly to buy a locked dongle in countries I travel to just to get the SIM card.
Some prepaid offers without a dongle are already available in Germany for some time now and you can find out more on the Prepaid Wireless Internet Access Wiki here. There's information about lots of other countries there as well in case you want to find out what's going on in your country. Have fun!