Your lawyer saw these posts this morning and she's happy to have gotten a break in the day to set folks' minds at rest about the copyright implications of blogging. The beautiful thing about copyright law in this context is: Jeneane is absolutely right, you create it, you own it. As the folks at Findlaw obligingly summarize, "copyright protects 'original works of authorship' that are fixed in a tangible form of expression. The fixation need not be directly perceptible so long as it may be communicated with the aid of a machine or device." (Savvy of them to recognize the "fixation" aspect of this form of authorship, wouldn't you say?) Copyrightable works include literary works and graphics, and these categories are very broad - computer programs and most compilations qualify as "literary works." Copyrights are automatically conferred as soon as the work is created. You own your posts, and this blog as a whole is probably a joint work, "a work prepared by two or more authors with the intention that their contributions be merged into inseparable or interdependent parts of a unitary whole" under the Copyright Act (although Jeneane likely would have additional rights arising from her efforts in fashioning such a fine forum). If you thought that a work had to be published or registered in order to enjoy protection, you are not alone; these are common misperceptions that flow from the way copyrights worked once upon a time. Now, a work enjoys protection even if it is never published or registered - although there are advantages to registration as discussed here. One powerful benefit of registration is this must occur before you can sue for copyright infringement. You can register at any time during the life of the copyright, which is during the author's life and for 50 years thereafter (slightly different rules apply to works made for hire, but the protections there are similarly long in duration). Registration costs $20 per application, and is pretty easy to accomplish. It may not be worth it though, unless you think people are out there actively stealing your stuff and you're hopping mad about it. Registration's main benefit is to let you sue, and to make it easier to prove that your copyrights have been infringed when you do (registration creates a public record of your rights, and creates some presumptions that will work in your favor should you ever need to enforce them through litigation). In other words, blog on, tickled that you don't need the likes of me to create your copyrights ;0>.
As for your use of others' copyrighted works, it pays to be cautious, use common sense and give attribution; a reference to another work, like citations or attributed quotes in an article, generally should not rise to the level of a "derivative work" that infringes the author's copyrights. Note that commercial publishers seldom leave that kind of thing to chance, however, and usually insist on getting an author's permission before a quote or other material is used. Also, the various linking practices seen on the web have given rise to all kinds of novel arguments by copyright owners. You could argue, for example, that linked material is incoporated into the linking web site, thus creating a new, derivative and improperly infringing work. Courts continue to wrestle with these issues, which I try to write about whenever something new or outrageous catches my eye (e.g., there were some interesting conflicting decisions involving eBay and Ticketmaster awhile back, and just this month, the Ninth Circuit held it was fine for a "visual" search engine to link to and display thumbnails of copyrighted images).
By the way, I think the Cafepress and blog archive tool ideas are fantastic (with all due licensing, of course)!