Collection of Interface Design Articles & Papers by Luke Wroblewski, Principle Designer at Yahoo! and design consultant. The papers provide tips, research, theory, and practical design insights. Below are 3 examples:

Blog Interface Design 2.0, co-authored with Jed Wood
Blogs have a wealth of information that is often buried due to their structure. This article suggests ways to make that information more accessible. Content Categorization techniques include tags, formats, and continuums. Tags can be more useful if presented according to relevance to the currently viewed content.  Tags should be actively managed to cull less useful ones and those that are used only once. Displaying existing tags for the author to choose from encourages reuse and enforces the current organizational scheme. Identifying the format of a post, such as "announcement", "article", "review", "link", etc., either by tag, or by some other type of label, can provide readers with a useful filtering mechanism. Blog Continuums track later blog posts that reference the current one, providing users a path to follow the evolution of an idea or story. Sparklines are a visual tool for viewing a continuum, and clicking on other posts within it. Valuable information is often hidden away in blog comments, but finding it can be made difficult by a lot of other tangential, off-topic, spammy, or personal comments Providing a rating system and other metadata to comments and a mechanism for filtering could help bring the most useful and informative ones forward. Often comments result in a conversation, the flow of which can be lost through a filtering mechanism, so identifying threads and providing a visual mechansim for navigating them could help readers follow along. All of the techniques suggested here require the creation of metadata about blog posts, and this metadata is best left to real people rather the automated processes. This can be done in three different ways, depending on the purpose of the blog and its content: entirely by the author; author initiated and approved, but incorporating reader input; and entirely reader-driven.
 
AJAX & Interface Design
Web development technologies that become popular in a short mount time, such as AJAX, usually become quickly abused as developers and clients race to deploy them. This article offers design tips for  more effectively using the technology. AJAX allows for "fast & incremental" updates to web pages without requiring the full page to reload. Because of this, users might not notice that the page has changed. Using a contrasting color or a simple animation, such as a fade, draws attention to the change. Designers should also strive to minimize disorienting screen "jumps" as larger or smaller new content elements replace old ones. Because AJAX applications behave more similarly to desktop applications than do traditional web pages, designers should look to the well-established desktop UI interface guidelines to inform their solutions. However, developers should keep in mind that user expectations are based on existing web conventions, and should not break from them lightly.

Web Application Solutions: A Designer's Guide (pdf), co-authored with Frank Ramirez
"Web applications are Web-accessible (deployed and/or accessed through a Web browser), Web-connected (utilize a http connection for information retrieval or display), and task-oriented (beyond the simple browsing of information) software." This guide presents many of the more popular tools for building Web Application Interfaces and the tradeoffs of each: HTML, DHTML, Remote Scripting, XMLhttpRequest, Flash, Java Applets, ActiveX, Java Web Start, and Smart Client. The pros and cons of each tool are presented as a matrix on single page for easy reference. The criteria are as follows: User Experience, Deployment & Reach, Processing, Interface Components & Customization, Back-End Integration, Uniques Features, Future Proofing, Staffing & Cost. The authors also provide a list of example websites and links to further reading for each technology. The Guide ends with an annotated list of other existing and upcoming relevent technologies

Luke Wroblewski's website also has links to online interface design courses, and he maintains a separate blog on interface design as well: Functioning Form