[ComputerNerd]
Another trick if you're using Windows is to go to Start > All Programs > Accessories > System Tools > Character Map. This has a list of all sorts of characters, including the a with grave. You can either copy it and paste it into a post or you can type in the number combination and it will appear in your text box.
For example: The key sequence for a with grave is ALT+0224. The numbers are keyed in with your number pad, which is the block of numbers to the right of your keyboard. For à, you would hold down ALT and press 0224 on the number pad and then release ALT.
ñ à ™ ë ΑΩ ...ad naseum.
[/ComputerNerd]