[gazment]

How much stuff have you downloaded? And do you download it only from Market? If so, click Market, then "My Downloads." This should tell you everything you've downloaded. You also have the option to uninstall whatever you want at this point.

Do you exit out of programs properly? Some programs (I wish all did, but they don't) have an exit option when you hit the menu key ie sprint nav.

You may need to uninstall some apps or use a task killer. A good task killer in the Market is TaskPanel its free and has very good ratings.

Every PC or Pocket PC uses up resources that will never be regained until a soft boot or restart is performed. Give turning off your phoneoff and turning it back on a shot.