I have created a Google Spreadsheet to keep track of my various coin holdings.

There is a separate sheet for each coin to keep track of where the coins are located (wallets, exchanges, pools, etc.), and a summary page to total everything up. I'm sure many of you have already done something similar.

What may be useful to others is that the spreadsheet has the ability to update itself using:
  The current BTC<->USD exchange rate from MtGox
  The BTC<->AltCoin rates from CoinChoose.com
  BTC, LTC FTC, BQC, TRC, and YAC wallet balances from blockchain explorer sites
  mmcFE based pool balances (a large number of altcoin pools are mmcFE based)
  BTCGuild pool balancess

To Do:
  Use additional exchanges to supplement MtGox when getting BTC<->USD price
  Coin balances from exchanges
  BitMinter pool balances

The code to do all the updates is written in Google Script and is open to examination.

Instructions:

  Access the document at https://docs.google.com/spreadsheet/ccc?key=0AtMHbfi9Ki83dHZUaWJ6ZGZXVVZsUFpSX016OG43dHc&usp=sharing

  You will not be able to edit the document or run the scripts until you make your own copy of this spreadsheet. Use the 'File -> Make a Copy' menu to make your own copy (you must be logged into Google or this menu funtion will be disabled)

  After you have made a copy, the "Update Prices" menu system will appear to the right of the Google Help menu after a few seconds

  Do not make any changes to the first sheet. You cannot currently rearrange coins without also adjusting code in the script.

  For the subsequent sheets (one for each type of coin), you fill out the rows describing your holdings as follows:
    Location: You can put any description you want here, except if you are entering a coin address and you want the script to get its balance, in which case you enter the coin address here.

    Holding: This is the number of coins you own in this holding. You can manually enter it, or if supported, it will be automatically updated for you.

    Holding Type: This is where you describe the type of holding. You can enter anything here, but these phrases have special meaning:
      Public Address: Indicates that you have entered a coin address in the location column.  For supported coins, the script will retrieve your balance for you from the appropriate block chain explorer.
      mmcFE API: Indicates that the holding is on a pool that uses mmcFE. mmcFE is the front end that probably 90% of pools use. You will also need to enter the next two columns (Pool API URL and Pool API Key), discussed below
      BTCGuild API: Indicates that the holding is on btcguild.com. You will also need to enter the next two columns (Pool API URL and Pool API Key), discussed below
 
    Pool API URL: Only applies when your holding is on a supported pool (currently mmcFE based or BTCGuild). Enter the URL of the homepage of the pool (eg: http://wemineltc.com/, http://www.fcpool.com/), etc.

    Pool API Key: The API key provided by the pool to use their API. Normally available from the "My Account" -> "Account Details" page on the pool

  Here is an example of how you would enter your BitCoin public address for automatic balance updating:
    Choose a row on the BTC (BitCoin) sheet and fill out these columns:
      Location: Your bitcoin public address
      Holding: You can leave this blank, it will update itself with the balance
      Holding Type: Enter 'Public Address' (without the quotes)
      (Leave the rest of the fields blank)

  Here is an example of how you would enter your wemineltc.com pool for automatic balance updating:
    Choose a row on the LTC (LiteCoin) sheet and fill out these columns:
      Location: Put whatever you want here. Eg: LTC Pool
      Holding: You can leave this blank, it will update itself with the balance
      Holding Type: Enter 'mmcFE API' (without the quotes)
    Pool API URL: http://wemineltc.com/
    Pool API Key: Enter your API key found at the "My Account" -> "Account Details" page on wemineltc.com. It will be a long random sequence of hexadeimcal characters.

  Here is an example of how you would enter a BTC holding that is not currently automatically updated (for example, on an exchange)
    Choose a row on the BTC (BitCoin) sheet and fill out these columns:
      Location: Put whatever you want here
      Holding: Enter the number of coins that are held in this location
      (Leave the rest of the fields blank)

  To perform the update, choose the "Update Prices" menu (integrated into the Google Spreadsheet menu to the right of the Help Menu), and then click "Update Exchange Rates" or "Update Wallet and Pool Prices" as appropriate. I will probably provide another menu option later that both in one click.

  There are plenty of coins, pools, and exchanges currently missing. I can add these depending on demand.

If you find this useful, please consider donating (BTC: 1L86EDpwUSm5GiJPZvXeCSXA2ebbEbBGBh  LTC: LQpXs9mzESQKwsZ3fTv8T8YW7KqmrQ2ibR)