I would like to use a new phrase every once in a while! I also sign business emails with “Best Regards” and “Thanks.” Surely all the brain power in the SDMB can come up with something more creative that is friendly, but not TOO friendly.
I had this dilemma a while back for all types of letters, business and for personal. Besides the obvious ones like the letters to my SO (Love) I always use a dash then my name, just as if it’s a quote. It gets rid of all confusion. Hope this helps.
-Clay
How about, “Fervently Yours”
I use “Regards,”
What about “Kind Regards” (after all, don’t you hate it when you get nasty regards?). 
Yr. most humble & obedt. servant
Maybe a little too familiar, but how about “Cheers”?
A second for the dash-and-name.
- KKB
“Sincerely” is usually personal/social letters. Business letters are often “Yours Truly” or “Very Truly Yours.”
(Miss Manners’ Basic Training - Communication, page 77)
I use
Very Truly Yours,
Ringo
I’ve used:
Regards.
Warm Regards,
Respectfully,
Imagining You Naked,
and,
From Your Stalker,
I use ‘With Sincerity’, a lot.
With Sincerity,
-Ashley
My personal choices –
For business use:
Sincerely [first contact, not likely to meet or recipient not named]
Regards [first contact, named recipient or not a ‘friendly’ message]
Kind regards [repeat contact, named recipient, ‘friendly’ message]
For personal use:
– Matt
MK
How about:
HUGS&KISSES!!! XOXOXOXOXOXO
and dot your i’s with little smiley faces 
Dear Oak Tree,
Thank you for shading me all these years. You have selflessly given of yourself to every season and…I love you. I’ll be dead soon.
Your faithful servant,
Tyrone Bibbins, esq.
P.S. Good luck to you and your people.
I must remember to write to thank that empty container of yogurt for being so full of yogurt when I met him.
I often move the “thank you for your time” from the last line and make it my closing.
Best Friends Forever,
Yer pal,
I sometimes use “Thank you in advance for your time and help” for my closing.
I just use my first initial, J, for internal email messages. For external email messages, I use my full name, title, firm name, location and direct dial telephone number.
Email messages aren’t to be treated like letters. They don’t require a formal closing.