The prices for these USB sticks has fallen through the floor! Culled from another thread on this forum I re-visited Littlewoods catalog website and note that they are offering the O2 mobile broadband pay and go USB stick for the princely sum of £10.

This is for an Huawei E160 rated at a maximum 3.6Mbps that supports HSDPA, UMTS, EDGE, GPRS, GSM. It also includes a non-SDHC MicroSD memory card slot so it can also be used as memory stick.

Interestingly, the USB stick includes "unlimited" WiFi from Cloud hotspots - although the reviewers seemed to have trouble making it work.

From £2 per day. Internet on the move. Unlimited Wi-Fi from over 6100 Cloud hotspots. Includes USB Modem, USB cable and SIM card. Easy to set-up on a PC or Mac. Minimum system requirements; XP Service Pack 1-3, Vista (32 bit) Service Pack 1, Mac OS X: 10.4 or higher.
The O2 tariff for Mobile Broadband is as follows:-
£2 for 500MB + unlimited WiFi Daily
£7.50 for 1GB + unlimited WiFi Weekly
£15.00 for 3GB + unlimited WiFi Monthly

For temporary or occasional use this would seem to be as good an offer as any - particularly at £10 for the dongle itself. That also sports WiFi and

O2's website shop has the same device on sale for £29.35