NIST has had a multi-year project to produce a web-based successor to Abramowitz & Stegun. They've gone public with the result, at http://dlmf.nist.gov/ I guess my expectations were impossibly high. The DLMF seems inferior to the physical A&S book in many respects. The web version does take advantage of various web possibilities. It has some very pretty graphs. It seems to work well in my ancient Mozilla browser. Moving the mouse near a formula brings a popup that explains the notations. They have dissed numerical tables :-(, and have minimized numerical methods. As a formula compendium, they give the basics, but most often refer to other references. Many of these are online. (You may need your credit card, but it's faster than walking over to the library.) They cover the bare bones of interpolation. Numerical integration of ODEs stops after basic Runge-Kutta. I couldn't figure out from the Table of Contents which chapter had Dilogarithm, but it showed up immediately in the index. The Dilog section is still missing the two-variable functional equation, D's most important property. Plus ca change ... On the plus side, they have extensive pointers to mathematical software, and have taken care to mark Free and Pay categories. There are several new chapters, including multivariate theta functions, and functions with matrix arguments. I didn't see a button for "download the whole thing so I can use it offline". Browsability is so-so: they provide Next/Previous buttons so you can read through a chapter, and lots of crosslinks. I found too little information per page for my taste, but tastes vary. In terms of usefulness, I dunno: If I want to learn about the hyperbolic-zilch function, I might do better to use Wikipedia or Google. DLMF does provide an overall viewpoint and organization, a roadmap for newcomers. As a youngster, some of my favorite books were the CRC mathematical tables book, and similar compilations. I first encountered A&S in college, and it had a similar "draw", the attraction of a big book of mysterious but accessible symbols and associated knowledge. DLMF doesn't have that feel to it. There is a companion book from Cambridge, which I didn't investigate. It may be that the time for this kind of object has passed, that the knowledge is better organized on Wikipedia & the like. If we need compendia of formulas, there will be online versions of Gradshteyn & Ryzhik, the Bateman project, and Jahnke & Emde soon, if not already. Overall, a worthwhile attempt. Have a look. Rich