Not available everywhere, but check - if it's where you are, you can get ADSL from
UK Online for £10/month for a 512kbps unlimited service. There's a £25 one off connection charge, but you get a free USB modem - or you can pay an extra £70 for a wireless modem/router.
They do faster speeds too, at reasonable prices:
2Mb - £20/month
8Mb - £30/month
(the connection charge for the 8Mb service is £50 not £25). They can do these prices because they have their own network (LLU - Local Loop Unbundling), which only covers 4.4 million homes in the UK, but it's worth checking if you're covered by looking on this
list.
Here is how they advertise their service:
Up to 512Kbps download speeds
Up to 256Kbps upload speeds
Up to 33:1 contention ratio
Unlimited monthly downloads
UK based 24x7 helpdesk
FREE email with 200Mb inbox
FREE spam filters
FREE web space
All together, a pretty damn sweet deal.
-simon