The following web sites offer lots of fonts from different foundries. Easy to find, try and buy almost any font.

My Fonts
www.myfonts.com
Use "What the font" feature, customize preview string, collect all your favorite fonts together in one place using Font Albums.

Font Pool
www.fontpool.com
Browse fonts by category or foundry, custom previews, for Windows and Macintosh.

Font Seek
www.fontseek.com
Search 20 font web sites and then download free fonts or buy fonts.

SoftMaker
www.softmaker.de
Currently offers a package of 10,000 fonts for just $49.95. I am not trying to talk you into buying it, I have just bought this package myself. It is just unbelievably cheap, almost for free. The package contains a lot of classic fonts like Bodoni, Baskerville, Caslon as well as various script and deco fonts. Every single font has a matching Euro currency symbol.

History and principals of font design. From Webreference.
www.webreference.com/dlab/9802/

Find out about companies that design fonts, buy fonts directly from the foundry. Partial list of cause.

Adobe Type Foundry
www.adobe.com/type/
Founders of Adobe Garamond, Adobe Caslon, Courier and thousands more. Prices start from $29 per 1 font. Adobe offers Adobe Font Folio and Adobe Type Manager.

Linotype Library GmbH
www.linotypelibrary.com
Founders of Gill Sans, Futura, Univers and much more. Prices start from $24 per 1 font.

Letraset
www.letraset.com
Offers several typeface collections. Prices start from $45 per 1 font.

Free Fonts
www.007fonts.com
www.abstractfonts.com
www.larabiefonts.com
Be careful using these fonts. Free fonts often have incomplete sets (no numbers or special characters) and poor kerning. In many cases font file format is good only for monitor display not for print. Mostly you will find fonts that represent handwriting and symbols.