Since we're starting to work out more of the bios of folks that aren't just the Musical 6, it might be good to have a dedicated thread for discussion along those lines.

For instance, some ideas we came up with so far, along with notes as to facts that have already been canonized (or will be shortly):

Carrot Top: Scientist, possibly with a doctorate ("Hoe Down"). Might lecture at Everfree Farming University. Uses her farm as a testbed for her technological innovations. Wants to prove that earth ponies backed by science can compete against flashier unicorn/pegasus magic.

Ditzy: Wants to be a wonderbolt ("Race That Ate Friendships"). Graceful, though with less stamina than Medley, strength than Raindrops, and speed than Dash. Raising Dinky Doo.

Bonbon: Runs the local candy store. Octavia's landlord ("Music of Ponyville") and Lyra's crush (ditto). Constantly innovating to discover new treats ("Octavia Sings the Blues"). Has her own garden for sweet herbs and other flavoring ingredients (ditto).

Noi: Foal who was skeptical about music until Bluenote got through to her ("Octavia Sings the Blues"). Loves helping her big sister Carrot Top on the farm, but is frustrated that she's usually considered to be too little to help.

Titchy Scratch: Younger cousin of Vinyl Scratch. Excited and energetic, and tends to repeat words a lot. Taking music lessons from Bluenote, though mostly it's just banging around on various instruments.

Raindrops: Maybe the Lunaverse/Dashverse characterization?

Twilight Sparkle: Brilliant magical scholar ("Busting Boasts"). Currently traveling the land to become a better mage, with the hopes of challenging and someday surpassing Vinyl.

Trixie Lulamoon: Daughter of the Duchess of Neigh Orleans ("Busting Boasts"). A talented showmare and something of an egomaniac. Traveling with Twilight.

Spike: Trixie's 'pet', though he's more of a partner in reality ("Busting Boasts"). He acts as a combination fax machine, ATM, and dispenser of sardonic advice.

Betty Buttle: Silver Spoon's maid ("Song of Silver"). Genuinely devoted to her charge, despite Silver's prickly exterior.

Feel free to post other thoughts below. After a few days, I'll add the profiles that there's consensus on to the Bible thread.

3298004 You... wrote Trixie is traveling with Trixie. I know her ego can be a bit big sometimes, but I don't think it's big enough to be its own separate entity. ;)

3298341 : Fixed :-)

Oh, where to begin (I do so love my background characters)

Cat Scratch: Vinyl's niece, works as Fluttershy's intern while also receiving training at Everfree Farming University. Rather clumsy but with a good heart. Has a colt friend called Ball Lightning ("Generocity Games")

Del Colt and Trotney: Cousins of Vinyl, seem to act as local jack or all trades, helping to clean out Sugar Cube corner ("Octavia Sings the Blues") and take Octy and Flutters to the ball ("Generocity Games") .

Prince Blueblood: Ruler of the principality of Monacolt and a well known philanthropist. Apparently a Jazz fan. Has a colt friend called Rising Star who is apparently an actor ("Generocity Games").

Ivory Scrolls: Mayor of Ponyville ("Music of Ponyville"), keen jogger. Has apparently not forgiven Octavia for her behaviour leading up to the Equinox and their relationship remains icy. Cheerilee is her daughter. ("Race That Ate Friendships").

Red Tape: The Mayor's assistant. Very by the book, Seems to have a crush on Lyra and some sort of feud with Vinyl ("Race That Ate Friendships").

Big Macintosh: A talented opera singer. Wants to travel the world some day. Seems to be romantically interested in Octavia and visa versa. Used to date Dash. ("Race That Ate Friendships"), ("Generocity Games").

Rarity: Local fashonista, Regularly raises money for a Canterlot orphanage. Friendly with Fluttershy. ("Race That Ate Friendships").

Mr and Mrs Cake: Local bakers, they seem to have a competition with Bon Bon and try to bribe Octavia to spy on her landlady for them. Regularly finish each others sentences. ("Race That Ate Friendships")

Angel: Fluttershy's pet and assistant. Has a phobia of magic due to rough handling by a trainee vet. Dislikes Cat Scratch. Adores Fluttershy. ("Generocity Games").

Ditch Digger: A local farm worker and part time athlete ("Race That Ate Friendships")

Suggestions for other characters: -

Ditzy: She was born with a congenital muscular problem which started to effect her in her foalhood. The most obvious effect is her eyes but she also has poor strength and stamina.
She was told that more than likely she would never be able to fly, never live a normal life. Her response was to say 'screw that' and dedicate herself to proving her doctors wrong. Maybe she has to work twice as hard to achieve the same as a normal Pegasus so she works four times as hard.
She wants to join the Wonderbolts partially to prove she can and partially due to a deep love of flying.
Her biggest fear is that her condition is hereditary and Dinky will be effected, the foal is approaching the age she first showed symptoms.
As I'm a rampant shipper I might romantically pare her with Dash. They are very competitive but have a deep respect for each other and their capabilities. Their relationship is probably on and off and they try to keep it secret (Although Dinky knows something is going on between her mother and Auntie Dash)

And now Hoe down is up

Caramel Apple - Big Mac and Applejacks cousin (refered to as such, exact relationship not know) works at Sweet Apple Acres. Was apparently helped out of a jam by Mac and feels he owes him. A womaniser (mareiser?) moves from partner to partner quite quickly.

Viola - The middle Philharmonica sister, described as wearing outlandish Garb (Hoe Down) and apparently have a busy romantic life (Generocity Games). 2-3 years older than Octavia.

Melody - Ocatvia's eldest sister and heir to her mothers title, described as being stiff and composed (Hoe Down). 5-6 years older than Octavia.

Fiddlesticks - A member of the apple family. Plays a fiddle rather well. Several Ponies note she looks rather like Octavia (Hoe Down).

Mr Scrolls - Ivory Scrolls husband, not a lot is known about him (How Down).

Sawdust - Vinyl's father. He runs a saw mill outside of Ponyville. Is apparently very work orientated. Doesn't understand Vinyl's music and tends to speak in carpentry metaphors. Vinyl seems to seek his approval. Wants his daughter to come home and work for him (Hoe Down).

Fertile Fields - Vinyl's mother. She and her daughter apparently enjoy teasing each other (Hoe Down).

The Scratch Clan - A large group of ponies mostly living and working in a saw mill outside of Ponyville. A mix of tribes although almost all white in colour. Vinyl's brothers Douglas, Alder, Yew, Spruce, Ash, Hemlock, Oak, Beech, Birch, Popular, Persimmon (Simmon), Cedar, Teak (Tichy), Hickory (Hick) and Mahongany (Mogwy) are all unicorns ranging from late 30s to new borns. (Hoe Down)