There are many similarities between online and offline DIY. Offline DIY is usually done, though, for private consumption such as in the case of a peice of furniture or a toy for one's child. Whereas, online DIY is not only done for private consumption but also for public consumption such as in the case of MySpace.
Justin listed the following comment but I haven't been able to allow publishing of comments yet so I thought I'd cut and paste it here in the meantime so I could respond--as if to one of the 12 or 15 grad students sitting on the other side of a live seminar roundtable...
This is a very thought-provoking answer for the following reasons:
1. It points out the key issue of offline vs. online--offline tends to be physical real world goods that are consumable/depletable so that their value/price is for each unit--a piece of furniture or a toy; online tends to be digital goods, some digital goods like knowledge are non-depletable, can be infinitely copied and might even grow in value with usage and network effects. Additionally, digital goods on the Web are freely distributable and repurposeable so that syndication, remixing, mashing up become ways to increase value.
2. It points out that public and private consumption patterns and behavior matters. The word "consumption" might be used in three very different contexts.
(a) Who profits or captures the value from the DIY activity? The manufacturer/producer/publisher and/or the user/consumer? Or is the re-distribution of value changed along with the beneficiaries? As a thought experiment, jot down the value chain and value-creating activities around a platform like MySpace. Who contributes, shares, benefits in this system? Are the benefits or profits monetizable or intangible? What are the network effects? Which become public goods and consumer surplus and which are privatized or monetized?
(b) When something digital and networked is "shared", is it "consumed" or used up? How does this change the economics and viable business models for Web 2.0?
(c) What are the different kinds of onlnine DIY that impact a business model and its cost structure? For exmple, what might be some of the key differences from an economic perspective between digital, interative, user-generated, rich user experience, multi-player, collective user value?