I know similar deals have been posted already but not this cheap as far as I can see (unless you count quidco discount which people have had probs with with O2 I believe)
Basically I went into the WInchester O2 store today looking for a cheap mobile broadband deal and the chap told me that the PAYG dongle is half price instore during January for only £10 and with this you get unlimited free wifi access via BT Openzone or the Cloud without topping up the dongle, great as for an emergency or for holidays etc. Mobile broadband rates are the standard;
Mobile Broadband Daily (available for 24 hours) - For £2 for 500MB + Unlimited Wi-Fi
Mobile Broadband Weekly (available for 7 days) - For £7.50 for 1GB + Unlimited Wi-Fi
Mobile Broadband Monthly (available for 30 days) - For £15 for 3GB + Unlimited Wi-Fi
Also has a micro sd slot so it can be used as a memory stick too which is handy.