Does anyone else have a hard time keeping exact track of their fiber intake? I get my lunch at this organic buffet place, and I try to guesstimate the amount of fiber I'm eating, but I feel like at the end of the day I could easily be 10g off or more. I don't think I'm ever getting too little fiber...but sometimes I'm not sure if I'm getting 35g or like 50g.

Oh, yeah. It sure isn't exact with me either. I guestimate usually too. I know and have 1 1/2 cups of All Bran Buds and that has about 26 grams of fiber right there. I figure anything else I eat (fruit, veggies etc) will put me over the top.
I think if you stay in range you don't have to worry about knowing exactly what you get.

the easiest way for me to know that i got at least 39g of fiber was to have that full 1 cup bowl of all bran bran buds. that is 39 g of fiber in 1 cup! put in whatever you like in there and well, anything else that has fiber during the day is just pure bonus.
i wish i had an organic buffet over here!!!!!! damn DC.
nyc has a lot of cool macro/vegetarian/vegan places. that is one thing that i do wish i had here.
the trick though at the end of the day is to make sure you get your minimum of 35-40g each day.

I've tried a variety of nutrition-tracking software (mainly on my PDA or phone) over the years when I was trying to gain or loose mass.
Most of these programs record fiber as well.
If you're not the type that wants to record everything you eat at every meal, I find keeping a quick note of lunch (or a picture from your phone) is a good way to journal, and then you can put in the specifics at night, or in the morning, when you have time.
I can assuredly say I get between 25-45g of fiber a day -- I try to lean soluble heavy, or I think that anything over 30g would kill me.

the trick is to get the same amount of fiber every day and not fluctuate it.
you want to regulate your body...not send it on a roller coaster waiting for x amt of fiber on day 10 and then y on day 11 and then z on day 12..........
this is a hard part but very important to regulate the poos......