[minbongie2004]

I've heard a few- companies like Play! and VGL (Video Games Live), I think they're American-based (not much use to me XD) but worthy for people north of the equator.

For me, I go to the ones held in Australia by Eminence I think they're great. If you haven't yet tried going to any of the concerts, I really recommend that you do! Typically they perform music from anime/games.

Here's an article from the news section on eminenceonline.com/passion. I've highlighted the important bits:

Performing in Sydney, Melbourne and Singapore (for the very first time!), ‘Passion’ is a concert series which combines talented musicians with powerful and evocative music from some of Japan’s most loved anime and video games.

Performed by a small ensemble, consisting of violins, percussion, guitar and piano, ‘Passion’ will feature the unique and innovative arrangements of memorable themes from games such as Chrono Trigger, Chrono Cross, Tsubasa Chronicle, Vagrant Story, Final Fantasy XII, Xenosaga, Haibane Renmei, Shadow of the Colossus, Super Mario Bros., .hack//Liminality and many more.
On top of the great selection of anime and games, we will also be performing selected classics from Walt Disney features.

With special guests Yasunori Mitsuda (Chrono series, Xenogears) and Hitoshi Sakimoto (Final Fantasy XII, Final Fantasy Tactics), ‘Passion’ will be without a doubt Eminence’s most exciting concert to date. Please join us for this world premiere, as you will not be disappointed. Visit the new Passion 'miniwebsite' for more details. Also, see our Passion FAQ for ticketing status and other relevant information.

You can find footage on youtube, I'll post it up later.