Rob said it all really. The way to make the most out of your bard is to go the route of RDD and Devestating Critical.
The only other considerations are how to make the most of it.
You might think of using weapons with a large threat range. Kukri are great for having that and being slashing weapons for you to give a keen edge
You may think of getting as many attacks per round as possible (dual-wielding, taking 4 warrior-class levels before level 20)
You may want to increase your attack bonus through spells, buffs, bard song and multiclassing.
And of course have a back-up plan against those creatures immune to critical hits. SoU's Wounding Whispers is a great spell here, you can practically let the enemy kill themselves if you back it up with damage resistance (Visage spells) and healing. Curse Song is also very effective here, but if you take this feat, don't take the Lingering Song feat as well. That may sound odd, but creatures can only be under the effect of one song at a time, and that's always the first they heard. Since at higher levels Curse Song deals damage, you don't want there to be any more time between songs than is absolutely necessary.
Of course, just because RDD is the most effective (definately nearing the point of uber, as is Dev Crit, depending on who you ask) combination you are not forced to use it. I think there's a beauty in a pureclass bard, or the bard/assassin as well. I wouldn't go bard/rdd/assassin though, death attacks are just as useless against enemies immune to critical hits, and the class only distracts from your main goal of causing them.
As a side note, I want bards to get their colour spray back. Advertised as the perfect bard spell in the BG series, and now it's gone
