Kevin Laws has released version 1.0 of his Cell Plan Tracker which is a customizable program to track how many minutes are left in your calling plan. This program has been under development for about a month now and looking through VisorCentral's boards it has many satisfied users.
It will track your data minutes used, Peak minutes, Off-peak minutes, roaming minutes, 411 calls and many more things. It is available for $9.95 at Handago.
This next program, TA is an interesting program which takes advantage of the call-forwarding features of GSM. Using this program, the Treo can conditionally choose to automatically forward calls to different numbers when you are busy, have no reply, or are unreachable. TA is made by m-internet.com limited. It is available for $9 at Handago.
Last of all there is a somewhat new site that is offering very cheap screen protectors. Free Screen Protectors sells incipio merchandise at extremely discounted rates. Using coupon code FREESP all you pay is shipping for screen protectors for almost any PDA model. The lowest fee for shipping is $6.95.