1. "That's What Friends Are For" - Dionne Warwick and Friends - 1986.
This would be good for a romantic friendship... an imaginary friend who helps with 'girly' things.
2. "I'll Be There for You" - The Rembrandts - 1995.
This is a really nice acoustic version, but may be a bit too branded with the TV programme "Friends".
3. "Lean On Me" - Bill Withers - 1972
4. "You've Got a Friend" - James Taylor - 1971
5. "Umbrella" - Rihanna - 2007.
This could be really nice for a imaginary friend who is not human I think. As it is not specific to a gender and is more current it would suit something really fictional. I don't know why!
Top hits when searched for friends on my iTunes.
6. "All My Friends" - LCD Soundsystem.
Brilliant song and really nice atmosphere. Might be a bit too grown up for talking about imaginary friends but the bit 'it gets tired but its better when we pretend' is really nice.
7. "We Are Your Friends" - Justice vs Simian
8. "We're Going To Be Friends" - The White Stripes
9. "Kids" - MGMT