Hatsune-san first hit shelves in 2007 on this day, making her program seven years old, although technically her outer persona is permanently sixteen years old. I know that Miku Hatsune is a polarizing figure - she's not a real person, although her voice bank was created by an actual voice actress, fandom's adoration of her can get overwhelming at times, and some people find her songs grating. Not me. Miku Hatsune was my first exposure to VOCALOID culture and I've enjoyed what fandom has created with her voice bank since then.
Some VOCALOID users have found a way to properly utilize Hatsune's sound bank and make some really great songs, either playing heavily on her computerized voice or downplaying it to sound more natural, which is a tough task in itself. They also make some really amazing music videos for her music, using the VOCALOID computer/video game programs commercially available to make very polished products.
If you somehow haven't heard a Miku Hatsune song in your life, here are some of my favorites to get you started:
Some of her best songs are duets - I especially love Hatsune's duet with fellow VOCALOID Megurine Luka, World's End Dancehall. Miku and Megurine's voices work very well together on this track. There are also versions where the main VOCALOID personalities sing this song together, and they're worth a listen, too.
If VOCALOID songs with stories sound interesting, the Story of Evil series is probably the best known in fandom and features Hatsune as one of the characters. Note: it's rather violent at times, deals a lot with death, doomed love, and incest, so keep that in mind when watching.
I think I'll celebrate Miku Hatsune the best way I can - by listening to some of her music. Thanks to sites like YouTube and NicoNicoDouga, that's not hard to do!