If you have an on-line slide rule site and would like to be listed then please e-mail me with the details and I will add you to the list.

• Giovanni Breda - Interesting collection of slide rules and mechanical calculators. While many of the rules are from around the world there is quite a concentration of interesting European rules.
• Nigel Bromley - Has a small primer on how slide rules work plus some information about his personal collection - no images.
• Guillermo Castarés - Reglas de Cálculo - Good collection of rules with descriptions in a well laid out site - a bonus for the Spanish speakers.
• Cal Clifford - Large collection of rules with descriptions - no images.
• John Current - Personal collection of rules with descriptions and images.
• David Davis - Has archival information about Dietzgen and Relay/Ricoh rules.
• Dave's House of Slide Rules - This site has a collection of Acu-Math, Dietzgen, Hemmi, Keuffel & Esser, Pickett, Scientific Instruments Co as well as a range of other rules.
• Dutch Circle of Slide Rule Collectors - This is the website of the Dutch Circle of Slide Rule Collectors. Here you can see a range of rules which were common in the Netherlands as well as other areas of Europe, in addition to the pictures of special samples there is also a history as well as a calendar of events of the group. The site is in Dutch, German, French and English and the webmaster is Otto van Poelje.
• Dennis Farr - list of rules in his personal collection with brief descriptions - no images.
• Jay Francis - The Slide Rule Guy - Small site with some information about his collection but no rules seem to be displayed.
• Michael Gährken - Personal collection of Aristo, Faber-Castell and Nestler slide rules.
• Chris Gillings - Personal collection of regular and specialist slide rules with images.
• Mike Konshak - Interesting collection of calculators for "Hairy-Eared Engineers", I guess those of us with a few years (and pounds or kilograms) under the belt may appreciate this reference. Mike's collection has a wide range of slide rules from manufacturers from all round the world, worth a look.
• Kung's OnLine Slide Rule BookMark - This site is a collection of links to other sites as well as a small amount of information about some personal rules.
• William Lise - This site has a large amount of background material on the Japanese manufacturers of slide rules. Put together by William Lise, who lives in Japan.
• Rod Lovett's Slide Rules - This site is a large collection of rules with information and images. Also includes a search faciliity for historical ebay prices
• Ron Manley's Slide Rule Site - An excellent reference site for slide rule collectors. Informative on a wide range of slide rules from a range of suppliers. Includes a summary of recent prices paid on ebay for slide rules.
• Eric Marcotte's Slide Rule collection - Personal collection with some good information and links.
• K&E Catalog Collection maintained by Clark McKoy. Comprehensive collection of Keuffel & Esser catalogues and a link to Michael O'Leary's K+E xref spreadsheet. Clark has now included his collection of K+E slide rule scans, worth visiting for any K+E collector.
• Dries Molen - A Dutch collector and former surveyor - Some information in Dutch.
• Andrew Nitiken - A collection of slide rule operations and links.
• Chris Osburn - A guide to scales and some information and images of the rules in his collection.
• Peter Owen - A collection of texts as well as information about and images of his rules.
• Giovanni Pastore - A list of his slide rule collection as well as some historical references. This site is in English, Italian, French, Spanish, German, Romanian and Japanese. Sort of puts those of us who are just English speakers to shame.
• Chris Sangwin - Slide rules and other mathematical instruments. Some information about historical rules and mathematics.
• Philip Scholl - Personal collection of rules with information, images and some documentation.
• Gordon P. Smith - Personal collection of rules with information and images.
• Todd Tolhurst - Personal collection of rules with information and images.
• Dave Van Domelen - A slide rule primer as well as a personal collection of rules with information and images.
• Kent Walker - Personal collection of rules with information, images and some documentation.
• Jason Waskiewicz - Personal collection of rules some information about scales.