I found this and I hope it's helpful:
This has been devised mostly thinking about and experimenting with my Nokia N97 and infamous low memory and RAM issues. Most of these ideas will be applicable across the board to many other s60 devices.
There are some things you can do to manage the C memory better/phone memory.
1. Clear your browser cache often
2. set different message allocation ( if you have not done so already)
messaging- options- settings- other ( set it to 999, and e memory)
3. Go to OVI store (app on your phone) and change that memory allocation for most apps.
opitons- account- settings- installation preferences
Note: Applications such as, Boingo, qik and jaiku CAN'T be removed from your phone, by who knows who's decision.
4. Remove Facebook, Accu Weather, Bloomberg, apps from the C drivve and reinstall them via OVI store and place them in the E memory/mass memory ( Specific to Nokia N97)
NOTE: If you are using Nokia Messaging application, it can only store data on the C drive so keep that in mind
NOTE: RAM is another issue with N97. Don't keep too many apps running at the same time as it will run out of RAM and either close all applications on the spot or crash the phone and result in restart.
BETTER RAM management : Here are some things to consider
also consider investing in the best taskman 1.99$ ( at the time of publishing, tho this may change in the future) in the ovi store or y browser (free) to manage your ram and all the apps that are runnig on the phone that you might want to close if you are not using them. It shows you how much free RAM you have, how much free phone memory and mass memory/memory card.
now y browser is free, it has a great amount of stuff you can do with it, but it is not as easy to use as best taskman and it does not look so pretty- that is if you care about looks over function. on Dr. Jukka's site you can also find Y- tasks which might come in handy for some users
This may not be a comprehensive list of things one might be able to do, but it is a good start to any such low memory trouble