Last night's episode of "How I Met Your Mother" was the 100th episode of the series, and might have been one of the best.
The "A" story of the show featured Ted on a date with guest star Rachel Bilson, who turned out to be the roommate of the future mother -- a character who's been referenced since Season1 but has never been seen on the show. When Ted picked up the yellow bus, then they showed the shot of it behind the kids, and Bilson's character said "that's my roommate's", it was a twist along the lines of the first episode's "and that's how I met your Aunt Robin" (and having an episode one-esque twist was a nice touch for this anniversary episode).
Realistically, I knew there was no way Bilson was playing the future mother, since that's not a role you cast with a guest star. Still, this is probably the most development in the series' major story since the Stella breakup.
As for the "B" story, it featured Barney trying to score with a new hot bartender (played by Stacy Keibler, who briefly attended Towson University at the same time as me -- yeah, I loved college), and having to ditch his suits to do so. I loved this entire plot, particularly the part where Lily tried to get Marshall to admit that the bartender was hotter than her (as an aside, I agree with Marshall. I'm more attracted to Hannigan than Keibler, but that's mostly because I have a thing for redheads and Hannigan played one of my all-time favorite TV characters). In the end, the Barney plot was resolved the only way it could have been: with a rousing, musical number. It was legen... wait for it...