A couple of new start-ups have appeared that we think embody the shape of things to come in the group-buy space.  First, a site that focuses on a specific industry vertical; a new B2B group-buy site for office workers and office managers called MarketSharing.

In public beta in NY, MarketSharing is now offering group-buy deals for online catering, courier services, the office donut run, and corporate discounts on gym membership to work off the donut calories.  We like this, a lot; our prediction is when a startup learns how to get group-buy into procurement departments, there’ll be a big bang in the B2B group-buy space.

The second group-buy site is also taps an industry vertical – this time, music.

Curated bundles of music can be purchased at group-discount at TuneBundle, the brain child of London-based entrepreneur Andrew Brackin. You can tweet to gain early access to the service (we like the tweet-for-access device, sweet).

Ok, so the idea of curated bundles of products sold online at group-buy rates is not in itself new; Mac fans will know of the long running mupromo.com – where bundles of software apps are sold heavily discounted prices – and unlocked when a certain number of sales are reached.  But the opportunity is to replicate this in new areas – and the curated-bundle + group-buy formula could potentially become very powerful;  the game-mechanics (time-limited, minimum number etc) may work with the model because it taps stuff we’re really interested in, rather than the impulse purchases of Groupon-et al.  If someone offered a Nadal tennis bundle, racquet with latest strip (minus Nadal himself) at a group-buy rate, we’d be in.

So thumbs up or down for group-buy B2B and/or curated bundles for high-involvement areas – all with tweet-for-access?