The internet is the best thing that has ever happened to us. Here's a small list of what I like.

Inspiration
Deviantart - The largest collection of artwork around. 
Behance - Bit similar to Deviantart, more quality, less quantity.
FFFFound! - Constantly refreshing list of somehow noteworthy images.

Advertising
AdsoftheWorld - My daily lunch of quality advertisements. 
Joelapompe - Copycats of advertising.
Advertising is Good for you - Nice, down-to-earth blog.

Design
CreativeBits - Discussions about Apple, internet, design and freelancing. 

Downloadables
BrandsoftheWorld - Free .eps logos. 
DaFont - Most famous font site I presume and quite right I'd say.

Information
Alexa - Get statistics about websites.
Google PageRank Check - Check your pagerank here.

Services
Analytics - Undoubtedly the best analytics tool for your website. 
Browser Size - Very simple tool to see browser size on your website. 
NetRenderer - See how your website works in other (old) browsers.
One.com - My webhost, I'm really satisfied with them.
Photobucket - Good quality service for uploading pictures (and videos). 
WhatTheFont! - Genius site for when searching a font.
WeTransfer - Free service to send large files.
FLVTO.com - Downloads videos/songs straight from YouTube.
QuieteTube - YouTube without ads. Not a fantasy.

Other
Clients from Hell - Stories contributed by designers about horror clients.
Google Ngram Viewer - Check the frequency of terms in literature.
Things Real People Don't Say About Advertising - Hilarious blog.