http://www.popfax.com/
You get a geo UK number (not an 0871, 0845, etc that's expensive and
difficult to call from abroad) and outgoing faxes are from EUR0.05/page.
There's a week's trial for EUR2, EUR18 for 3 months or EUR50 for 12 (all of
which includes unlimited reception and some sending credit).
Reception is in PDF to your email address, or you can view your in and out
boxes on the website. You can send directly from all sorts of formats (MS
Word, PDF, Postscript, OpenOffice native, JPEG, BMP, etc). (I think there's
an option to receive in TIFF too, BICBW)
I've been very happy - even sending to Africa (where frequently line quality
of VoIP offerings is terrible) it worked just fine. The destination fax
machine usually rings not more than 5 mins after clicking 'send' on the
website.
I can't vouch for long-term reliability (only been with them about 3 months).
