aww you DON"T want to get me started on Birthdays,, I once hung an entire office in black crepe and carved tombstones out of styro foam for a 40th birthday, passing out black arm bands for the entire staff to wear and attaching a few hundred ballons to a bottle of prune juice and a flashing sign to the hapless recipients door, arranged the "mourners" outside the poor guy's office and had them wailing and crying, and whenpeople asked who the black arm bands were for, everyone had a very good time mustering their saddest face and stating quietly,, "oh Bob is 40 today,,sniffle sniffle:
My birthday celebrations were legend, because I treated each one individually, but it WAS the little things that counted, a group email to everyone BUT the birthday girl/boy reminding them to wish so and so a happy birthday, an organized effort by the office staff to "pitch in" and help the birthday person on their special day so they could leave early, and a small short Individual celebration for each birthday,, I mean come on, don't ya just HATE those,, "okay everyone amble to the breakroom it's time for this month's birthday cake", how much nicer to have a coworker addressed by everyone in the work group, (due to your well placed and easily advance scheduled email) with a cheery happy birthday.
I solicited a movie theater in our area for free passes,and got them, and each birthday celebrator got two tickets to the movie of his/her choice and also had a similar success with a florist who our corporate account was placed with, it was great advertising for him and besides we were a valued customer I had a magician come in one day and do a short demo show for one employee who's hobby was magic, (his angle was leaving behind cards for our very baby boomer group who had children JUST the right age for birthday parties. I arranged a free limo ride home for a birthday celebrant who'd happened to mention that she'd never ridden in one and the limo guy was pleased as punch when that twenty minute ride turned into five bookings for proms and weddings because his involvment at the company was so well known.
Creativety and low maintenance is the key for me,,, The Group emails were advance scheduled for the entire year in about an hour, making me look like I never forgot anything and the deliveries made by the florist were up to him, relying on what he had in stock and were often very beautiful and interesting. (although there was that time the biggest brawniest guy in the place got that teacup of pink sweatheart roses, so oversight is still an issue

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You'd be amazed at what you can get, from local people who know your business and are eager to do business with you!
In short, get zany with the thing, you'll be far more appreciated for it than you know....
My four pence
Andrea