Nice ways to cheer for a friend running a marathon?

Also, please, please never use the phrase "almost there." Until your runner is turning off his Garmin, he is not almost there.

Take pictures of him, and try to make them flattering. Race pics are pretty expensive, and I usually look like I'm about to keel over. Bring a nice camera. Pic a spot on the course where he will be approximately a half-hour after sunrise (when lighting is optimal - not too dim but not too harsh), and when he comes by you cheer for him, wave, get him to smile, and get a pic. Have backup food (gels) and water for him. Races provide this, but sometimes run out, and that can suck. Also have something he can snack on afterward in case their post-race offerings are not great. Have a planned meeting place after the race, and some way that you can find each other. Some races are good about having a designated meeting area, but sometimes it is just a parking lot where 20,000 other runners are trying to meet their friends and family. My running partner has parents that love to cheer him on, and they carry a stuffed animal on a stick (so it is approx 8 ft tall) so he can spot them when he is going by in the race and so he can find them afterward. Carry comfy shoes for him for afterward, and possibly a change of clothes. Running in cooler weather you get sweaty, but then when you stop you are freezing. Even in warm weather, you are soaked in sweat. Having a t-shirt and flip flops (or fresh socks and sneakers) can make the walk back to the hotel/car/whatever much nicer. Also, the apps that races provide track runners are not always accurate and up to date. The text alerts I've signed up to receive have sometimes not come through, or come through significantly after the runner crossed the checkpoint/finish. Don't rely on it 100%

My incredibly awesome Bear waited at the 12 mile point for me and besides the sign/smiling/kiss I got when I greeted him, HE HAD ICE AND WATER waiting for me. Yes, it was so wonderful I am using shouty capitals. It is also really cool after that to get to the finishers area to meet your finisher and celebrate with them.

Use your app to meet them along the route and cheer them on. Your presence will be wonderful, but goofy signs and cowbells always make it more fun. Have a bag at the finish line with a change of shoes (I like to slip into flip flops) and, a sweatshirt/sweater (they will probably be cold once they go back inside for lunch). Also, baby wipes (or a wet wash cloth stored in a ziploc) to wipe off their face after the race. Wonderful in hot weather (when you'll be sweaty) or cold (when your face will be crusty and salty). And perhaps a small first aid kit? After my first (and only, thus far) marathon I had a huge blister on my foot that I absolutely needed to drain before I could even wear flip flops. Fortunately, a pin and a few band aids were close at hand. Also, don't forget to cheer on other people when you're waiting for your friend! It's fun when people are calling out your number/name/phrase on your shirt and you don't even know them! Have fun!

Mile 20. That's the Wall time for most people, and seeing a friendly face there would give most a boost. You could also bring along a banana for them!

Cheering for your friends is great, but they have to notice you! So visibility is key both on the route and a the start and the end - so perhaps dressing up on a single bright color, having a big flag, a sign, baloons or inflatable animal so your friend can immediately recognize you in the crowd?

Also, don't forget to cheer on other people when you're waiting for your friend! THISTHISTHIS. It's hard running a marathon; it's dispiriting running past silent spectators. For me, it's miles 21-24 that are the hardest. Over the 20-mile barrier; but not yet up to the "just one more to go" 25-mile mark. Support there means the most. Before: depending on the size and security setup of the event, you may not be able to enter the start area. If you do: the period before the start is a mixture of nervy anticipation jitters and portapotty queues. Seriously: pre-race peeing, really important. Offer to stand in line. After: your runner might be a bit spacy. It's draining both physically and mentally. So be prepared to guide them: know the layout of the finish festival. Where can they get water? Have a bottle ready, but also be ready to get more. Where can they get a snack? Fuel on the course tends to be sugar-based: Gatorade, goo, bars -- I often find a salty snack like pretzels or chips is very welcome. Where are the toilets? If they tend introvert, maybe scout a quieter spot where they could chill out and/or stretch. Also: scout the best/quickest/least crowded way out of the finish festival. One other thought: don't forget that the race itself is preceded by months of long, hard, and maybe solo training runs. Consider if there's also support you can provide there? (For example: having a "support car" helper enables more and different training routes because you can have them shuttle you out to the start of a long A-to-B route and meet you at the end.)

Oh, and http://ask.metafilter.com/251645/Gift-and-or-ideas-for-girlfriend-running-PHL-marathon in which I see I made similar suggestions.

What race is it? Many races have courses that you can spectate at multiple points. If your friend can tell you roughly what pace they are aiming for, you can try and show up with funny signs at each point. To be honest, I am almost never hungry after a marathon. Find out your runner's specific details, and maybe book the dinner for much later in the day. Also, depending on the course, it is almost always going to be easier for your runner to spot you than it will be for you to spot them. Wear something BRIGHTLY colored or outlandish.