The table linked by Bill D shows only the ANSI character set - decimal char numbers up to 2⁸-1. Very nearly all fonts should have most of these, although some "glyph substitutions" may be present in some fonts.

The table is actually a "composite" of Latin 1 and Symbol fonts within this range, but it shows only characters that can be inserted into html using the Alt-NumPad method. It doesn't represent all the characters that Georgia (584 char in my Adobe face) or Verdana (~600 char in my TrueType face) can represent in a posted web page, so it's not really a test of "how good" a font is for use in a browser.

ARCANE TRICKERY:

In most recent versions of Microsoft Word, if you type the hex code for a character, and then key Alt-X, the code will be converted to the Unicode glyph for the character for that code number. Once you get the character you want, you can copy it from Word and paste it in a post. Only the character code is actually "entered" into where you post it, and the font that's set or specificed determines whether it will "look right." Anyone with a browser/font setup that can "see" that character will get it correctly when they view the web page.

For an additional way of using this little "trick" you can copy a character from a web page whether or not it displays correctly in your browser. Paste it into Word and set the cursor immediately to the right of what you pasted. Click Alt-X and it will be transformed into the hex code for the Unicode character.

Click Alt-X again, to change it back to a "glyph," and then change the font until you find one that displays it correctly, if necessary.

Note that this works only in some Word versions and full function may require that you have current Office updates regardless of the version you have.

If you're not "fluent in Hex" a conversion chart may come in handy.

(Georgia is, in the face I have, an "augmented character set" approximately equivalent to Verdana as far as characters represented, but it doesn't appear to be contained in the Microsoft default font set(s) since I don't have it in a TrueType - the only kind Mickey distributes willingly. It's probably a pretty good choice if you have it. The font does - in my version - contain things like the "oganek and other diacriticals" missing from the chart.)

John