I've mentioned it before and I'll mention it again... we are using an online service to keep track of all our RSVP's. In my very limited experience with keeping track of a large quantity of RSVP's this seems like the best option (not that I've ever done it before or anything).
The service we are using is AnRSVP (just in case you are interested in using it too)
First, the problems.
Everyone on your guest list has to have a different first and last name combination. This didn't work out for us. So, say for example you have 2 people you are inviting that are both named John Smith... that's not allowed. We had not 1, not 2, but 3 instances where people had the exact same name. It was an easy fix for us though.
One of the places this came up was with a child having the same name as my grandpa. To fix this problem I grouped my cousin with the rest of his brothers and sisters. So instead of it just saying "John" on the first name spot it says "John, sisters name, other sisters name" and I gave that line an invite count of 3. I know that family can't make it already so I wasn't too worried about how I set it up.
The other problem was with John's side. He has an uncle with the same name as his grandpa and an aunt with the same name as his grandma.
The solution to this was also an easy one. John told me that his grandparents wouldn't be RSVPing for themselves anyways so for the first name for his grandparents I put Grandpa *his first name* and on the next line Grandma *her first name*. This way the aunt and uncle (whom will likely have enough knowledge of the internet to RSVP for themselves) can RSVP for themselves using their actual names and we can just do it for his grandparents.
The other annoying part was that I put the names into the online program in the order that I had them listed on my list... so according to families. The program jumbled them all up into an order I couldn't understand. So eventually I just put them in alphabetical order to make people easier to find.
I also put the names in individually,,, I know you can also do some importing of stuff but I figured I would have more control over the names if I just did it myself (plus, on the document we were keeping track of their names I also had written in if they were my aunt/uncle/grandparent.... I would have just had to do some editing anyways. It took a bit of time... not a lot. What did get frustrating was that I missed some people and then because the list wasn't ordered the same as my hard copy it was hard to see who I missed putting in. But I eventually figured it out and now our RSVP list matches our hard copy list.
The program keeps track of your RSVPs for you! I don't have to worry about forgetting to mark someone down as a yes and what kind of allergy they have.
You can make your own questions to accompany your RSVP.
We have just 2 questions...
1) If there are any allergies (our caterer is willing to work around these)
2) What kind of song(s) they would like to dance to that night.
The program also lets you know how many invites you need to send out. I think we ended up with 94 that were going out. It helps when you need to know how many invites you should be printing or how many envelopes you need to buy (it's just too bad John didn't have his list finalized before I ordered the invites and envelopes).
The online service gives us a unique (but easy to type in) URL that we included on our invites so that guests shouldn't have too hard of a time RSVPing.
According to the site as of right now we have 17 people attending our wedding. Should be a small and intimate wedding with only 6 songs people want being played during the dance portion. People likely don't realize that we need them to respond with a no if they aren't coming. But, about 3 or so weeks before the wedding we will get on all these people that haven't responded and likely just do it for them. Hopefully, we get a lot more responses to make this job a little easier on us!