I don't seem to see it like that.
Yes demo always gives as first artist one you type, but the list that follows has different artists.
May be we are aiming for different things.
Any way I did get it working with echonest as the source, as you did not seem keen on this method.
It uses one call to echonest for 100 tracks and a youtube search on track change.
You can see the results I get from the results of two searches for madonna similar artists radio below.
It seems reasonably similar to how I remember foo_lastfm_radio.
It will be interesting to compare it with your way.
You can also apparently change the variety of artists and song_hotness returned, but I haven't tried that.RESULT 1 echonest madonna similar artists radio
Madonna Don't Tell Me,Céline Dion Because You Loved Me,Gloria Estefan Mi Tierra,P!nk Try,Emma Bunton A World Without You,Cyndi Lauper Time After Time,Kelly Osbourne Come Dig Me Out,Annie Lennox A Whiter Shade Of Pale,Madonna Sorry,Darren Hayes Explode,Sophie Ellis-Bextor Get Over You,Gwen Stefani Cool,Tiffany I Think We're Alone Now (Re-Recorded / Remastered),Rihanna Pour It Up (Explicit),Dannii Minogue You Won't Forget About Me,Janet Jackson That's The Way Love Goes,Madonna Die Another Day,Cher Woman's World,Spice Girls Who Do You Think You Are,Kim Wilde You Came (2006 - Album Version),Kelly Osbourne Shut Up,Cyndi Lauper True Colors,Melanie C Never Be The Same Again,Kylie Minogue If Only,Madonna Girl Gone Wild,Rachel Stevens I Said Never Again (But Here We Are),Taylor Dayne I'll Always Love You,Natalie Imbruglia Wrong Impression,Darren Hayes Black Out The Sun,Spice Girls Spice Up Your Life,Emma Bunton What Took You So Long,Martika Cross My Heart,Madonna Open Your Heart,Christina Aguilera Beautiful,Britney Spears Work B**ch,Paula Abdul Knocked Out (Single Version),Gwen Stefani Rich Girl,Martika Flow With the Go,Spice Girls Goodbye,Sophie Ellis-Bextor Catch You,Madonna Papa Don't Preach,Kylie Minogue Kiss Me Once,Cyndi Lauper She Bop,Melanie C Northern Star,Jennifer Lopez On The Floor,Rihanna We Found Love,Dannii Minogue All I Wanna Do,Robbie Williams Go Gentle,Madonna Frozen,Paula Abdul Vibeology,Kylie Minogue Get Outta My Way,Spice Girls Holler (Album Version),Kelly Osbourne Contradiction,Michael Jackson Thriller,Paula Abdul Forever Your Girl (Single Version),Madonna Like A Virgin,Darren Hayes I Miss You,Britney Spears Toxic,Kim Wilde Kids In America,Emma Bunton What I Am,Kelly Osbourne Uh-Oh,Madonna Like A Prayer,Roxette The Look,Cathy Dennis Touch Me (All Night Long),Geri Halliwell It's Raining Men,Emma Bunton High On Love,Cyndi Lauper Girls Just Want To Have Fun,Lady Gaga Applause,Melanie C Think About It,Madonna 4 Minutes,Darren Hayes Stupid Mistake,Sophie Ellis-Bextor Runaway Daydreamer,Gwen Stefani The Sweet Escape,Kylie Minogue Into The Blue,Rihanna What Now,Kelly Osbourne One Word,Taylor Dayne Tell It To My Heart,Madonna Take A Bow,Spice Girls 2 Become 1 (Single Version),Martika Toy Soldiers (Single Version),Belinda Carlisle Leave A Light On,Cyndi Lauper I Drove All Night,Melanie C Weak,Cher Strong Enough,Madonna Music,Christina Aguilera Your Body,Belinda Carlisle I Get Weak,Taylor Dayne Love Will Lead You Back,Cher Believe,Spice Girls Too Much,Emma Bunton Downtown (Single Version),Martika Love...Thy Will Be Done (Single Version),Madonna Live To Tell,Christina Aguilera Fighter,Paula Abdul Cold Hearted,Gwen Stefani Hollaback Girl,Robyn Dancing On My Own,Kylie Minogue Fine,Spice Girls Stop,Sophie Ellis-Bextor Young Blood
RESULT 2 echonest madonna similar artists radio
Madonna Like A Prayer,Gwen Stefani Cool,Cyndi Lauper She Bop,Cher You Haven't Seen The Last Of Me,Taylor Dayne Don't Rush Me,Tiffany Here In My Heart,All Saints Never Ever,Britney Spears Gimme More,Madonna Hung Up,Jennifer Lopez I Luh Ya Papi,Céline Dion It's All Coming Back To Me Now,Lady Gaga G.U.Y.,Robyn Cobrastyle,Kylie Minogue Sexy Love,Roxette It Must Have Been Love,Janet Jackson What Have You Done For Me Lately,Madonna True Blue,Cher I Hope You Find It,Kim Wilde Cambodia,Natasha Bedingfield These Words,Kylie Minogue Kiss Me Once,Anastácia Paid My Dues,Cathy Dennis Touch Me (All Night Long),Gloria Estefan Mi Tierra,Madonna La Isla Bonita,Melanie C First Day Of My Life,Cyndi Lauper True Colors,Christina Aguilera Genie In A Bottle,Taylor Dayne I'll Be Your Shelter,Natalie Imbruglia Torn,Lady Gaga Poker Face,P!nk Raise Your Glass,Madonna Material Girl,Robyn Call Your Girlfriend,Cher Take It Like A Man,Sophie Ellis-Bextor Runaway Daydreamer,P!nk Try,Gwen Stefani Luxurious,Annie Lennox Why,Céline Dion I'm Alive,Madonna Take A Bow,Kylie Minogue Love At First Sight,Ashlee Simpson L.O.V.E.,Janet Jackson That's The Way Love Goes,Britney Spears Criminal,Lady Gaga Bad Romance,Melanie C I Turn To You,Gwen Stefani What You Waiting For?,Kim Wilde Kids In America,Madonna Don't Tell Me,Robyn Konichiwa Bitches,Cher Woman's World,Britney Spears Oops!...I Did It Again,Dannii Minogue I Begin To Wonder,Roxette Listen To Your Heart,Taylor Dayne Love Will Lead You Back,Madonna Sorry,Britney Spears Perfume,Kylie Minogue Into The Blue,Cyndi Lauper The Goonies 'R' Good Enough,Martika Toy Soldiers (Single Version),Madonna 4 Minutes,Cher Gypsies, Tramps And Thieves,Kelly Osbourne One Word,Taylor Dayne Tell It To My Heart,Gwen Stefani Early Winter,Sophie Ellis-Bextor Young Blood,Britney Spears Circus,Madonna Live To Tell,Jennifer Lopez On The Floor,Christina Aguilera Beautiful,Céline Dion That's The Way It Is,Lady Gaga Do What U Want,Robyn Be Mine!,Kylie Minogue Sexercize,Roxette The Look,Cyndi Lauper I Drove All Night,Madonna Ray Of Light,Cher The Shoop Shoop Song (It's In His Kiss),Darren Hayes Bloodstained Heart,Janet Jackson If,Kylie Minogue I Was Gonna Cancel,t.A.T.u. All The Things She Said,Kim Wilde You Keep Me Hangin' On,Madonna Die Another Day,Cyndi Lauper All Through The Night,Christina Aguilera Hurt,Taylor Dayne Can't Get Enough Of Your Love,Melanie C Never Be The Same Again,P!nk Just Give Me a Reason,Madonna Holiday,Robyn Dancing On My Own,Natalie Imbruglia Wrong Impression,Darren Hayes Black Out The Sun,P!nk So What