Weddings are the embodiment of traditions and practice - all in the name of love of course! The walk down the aisle, the exchanging of vows, the celebration afterwards...all of this has been done for centuries before our time. (sorry, back to the point now:) So whether your reception is super formal or the opposite, there are customs and traditions that have been established to help you express your joy and excitement for your special occasion. And with that said, wedding invitation etiquette can become an intimidating subject for some folks. There are so many formalities involved! Who to invite? How to address the invitation? What titles should be used? What is an inner envelope? How to deal with uninvited guests? Am I supposed to spell out "four o'clock" or is it OK to simply write "4:00"? What is a pew card? AHHH!
Since info on the web can be sketchy sometimes, I've browsed through and found a few trustworthy sites that I hope will assist those in need!
Here they are:
The Knot - The Q&A section on invitations is lengthy and there are bulletin boards where you can post and search questions by other "knotties".
Real Simple - I like the advice here...Be creative but don't forget the essential information! Buzzle - The Tips, Rules and Etiquette section is especially helpful. Wedding Paper Divas - Plenty of information to help you gather ideas, become informed and plan your stationary needs.
Wedding Tips - I would suggest subscribing to the RSS feed for the daily tip of the day, there's nothing like learning something new every day.
Above and beyond all of this, your only true limitation is your imagination and you should have fun with the project of creating your wedding invites. 
