Electronic Component Suppliers
All About Circuits is an extremely active electrical engineering online community that provides both interesting content and useful resources for Electrical Engineers.
Newark Newark is an expansive online catalog of connectors, Arduinos, and electrical components.
PEI Genesis Custom connector & cable solutions for harsh environments. Shop electronic components to find your custom connector solutions.
Hobby Engineering  Hobby Engineering is a site slanted towards the hobbyist. This site carries some useful items that can be harder to find from other providers who are catered towards the corporate customer. it also has a good supply of micro-controllers, robot kits, parts, ad miscellaneous components and tools.
All Electronics  All Electronics has an incredible selection of many of the useful items you would use to build your project. They are very inexpensive and it is easy to find your way around the site. This site also has a "consumer comments" section where the consumers get to talk about the quality of the product and more.
BG Micro  BG Micro is a cool site for rare and pretty neat gadgets as well as a nice selection of a lot of the items one will need for a weekend project. There is also a very nice search engine at the top which lets you search for an item you can't find on the left.
Jameco  Jameco has a very nice site catalog. It's not very big that you suspect a forest was sacrificed in its making. I has great color photos with relatively easy to find components. This is one supplier with a low price guarantee which means that if you can show a part offered for less, the lesser price is honored. Jameco also provides lower priced generic products as well as name brands.
Digi-Key  Digi-Key is a large distributor of components from various manufacturers, offering a very large catalog with lots and lots of choices. However, the site uses small print that might be hard to read. The catalog includes line drawings but o part photos, but it does do an excellent job of labeling the parts. Overall, Digi-Key has a huge selection of products, but they might need a little looking to find them.
Mouser  Another large distributor of components from various manufacturers is Mouser. I like how Mouser's site allows you to compile separate orders for different projects. You can come back as many times as you like to complete your order and make your purchase. We also like how Mouser label parts because the labels are easy to read and provide a lot of information about the specific part. Like Digi-Key, Mouser provides a very large catalog.
Electronic Goldmine  If you are in the market for bargains, try Electronic Goldmine.. This online store often offers specials that can save you money. Based in Scottsdale, Arizona, Electronics Goldmine offers great help with international orders and also offers wholesale items on auction on eBay. Quick Tip: Try clicking Electronic Goldmine Treasure Ball for the best deals!
Maplin  The British supplier Maplin has stores scattered around the U.K. and also offers an online store. Unlike electronic gadgets and appliances that operate on different voltages in European countries, electronic components are pretty standard. Although Maplin will ship overseas, you might want to check out U.S. Suppliers first.
Sparkfun  Sparkfun was originally a PCB Manufacturer, and turned in to a company well beyond their expectations! They have a large variety of PCBs, LEDs, and MANY more everyday electronics components. The site is well organized with so much to choose from!
Online Components Online Components has over 350,000 parts in stock and are an authorized distributor for several manufacturers.
Eaton Electronics Eaton offers a broad range of electronics components that include power magnetics, circuit protection, supercapacitor and terminal block products. These products serve customers in computing, consumer, energy, industrial, medical and transportation markets.
References  Instructibles