If you're running a rooted HTC EVO 4G and have had complaints about your signal strength, battery drain, or anything involving the transmission speeds, there may be a solution to your woes that does not involve throwing the phone off a tall building to make it go faster.
Version 2.15.00.08.08 baseband is out, and some are seeing better speed, signal, battery life, and responsiveness. Your mileage, of course, may vary based on phone, HW revision, ROM, cell signal strength, and time of day; however, generally newer radio firmware = better radios.
A warning, though: flashing a radio involves doing the only thing that can potentially brick an HTC EVO 4G, so make sure you have a full battery and the restraint to not pull it out of the phone if it doesn't appear to do anything for several minutes.
As with any flashing, it's a good idea to have a recent Nandroid backup. Additionally, make sure you have a backup of your WiMAX keys (some recoveries will back this up by default, but don't risk it) because if you lose them, your 4G will no longer work.