I have multiple online resumes, which I customize for specific job applications. Unique URLs for each with integrated cover letters gives me tracking, and I've had almost a 90% response rate (defined as getting a response and/or first phone interview) with this approach.

Plus, I can design responsive one-pagers easily with my own design tool, which is also coincidentally where I host the resumes. Customization is mostly the cover letter and tweaking specific job history accomplishments to focus on what a job posting is looking for, but often I've done custom designs as well.

One big issue I find is that many online job submission forms still only have an 'upload .doc or .pdf resume' button which accepts a file. Once you get around this and have actual people click the link, the results are usually good. I will usually post a text-only version with a header to the effect of "Hi there - please view this resume online for easier readability & sharing. [link here]"