Mobile phone plan comparison site.

[randomness]

One of you out there was telling me about a comparison site you really liked. As my brain resembles a screen door (not even a sieve), I have forgotten the site.

Anyone willing and able to enlighten me? My mom has inherited a cheap Nokia GSM phone and wants to get service for it. (Yes, one of the considerations will be whether it's cheaper to get a bare SIM for it or a "free" phone package.)

Thanks in advance to all!