When it comes to planning story times, spread sheets are my best friend.
For babies, I have a list of all the books I use and the date of the last time I used them. This ensures that I don't do Dear Zoo and Moo Baa La La La every single week. I also like it because I can sort by date (which books haven't I done in a while?) or by author or title (when was the last time I did X?)
Also, after story time is done, I have another spread sheet where I write down who came every week. Now, we don't register for our programs so it's not an attendance record, BUT with the babies, I need to know their names. (If nothing else, because the welcome song gets individualized.) Every week before story time, I look to see who's been coming the last few weeks, so names are fresh in my mind. This makes me look like I have a super-memory for names.
Even better is my spread sheet of rhymes! This one is shared with our whole department. It's an Excel workbook and different pages are for different age groups and languages (we have a French-English story time, too.) So we have the rhymes and then another column categorizes them (Mother Goose, knee bounce, action, clap, song, etc) so if I'm putting my rhymes together and think "Hmmmm.... I need another tickle here" I can sort by type and scan through the tickle rhymes and then copy-and-paste them into my handout. It's also great because it's a shared file, so it's easy to share rhymes with coworkers. It's always so frustrating when you're planning a program and think "wait! What was that cool Jellyfish counting song that Lauren always does?! How does that go?!" Now it's in the sheet so if Lauren's not there, I can still find it and use it.
I realize that planning story time via spreadsheet might seem a bit anal (but, like Millicent Min, I don't think that's a bad thing) but I find it really useful.
Do you use spread sheets or do you have something else that works really well to keep your story time planning organized?