Cellbits.com currently offers 9 screen sizes for cell phone wallpapers, screensavers and background downloads. See the partial list below for mobile phones that have these screen sizes. Consult your operators manual or cellular carrier website if you don't see your phone listed. Custom sizes may be available. Contact: customer_service with requests.

Android Phones
The Android phone operating system actually requires a wallpaper background larger than the listed screen size because of the sliding desktop effect it uses. So, 320x480 screens need wallpaper that is 640x480, for example.

320 x 480 (640x480)
HTC: G1/Dream, Droid Eris, Hero, Magic/MyTouch
Motorola: Cliq
Samsung: Behold II, Galaxy/i7500, Moment

480 x 800 (960x800)
Google Nexus One
HTC Evo

480 x 854 (960x854)
Motorola Droid

240 x 400
LG: CT810 Incite, CU915 Vu, CU920 Vu, GR500 Xenon, GT505, GW520, KB770, KC910/910i, KE850, KE990/990c, KF900, KP501, KP502, KU990, KP500 Cookie, KP501, KP502, KU990/990i, LG-KP570, LG-9700, ME850d, MX830, U990, VX10000 Voyager
Samsung: M8800 Pixon, SGH-A867 Eternity, SGH-A877 Impression, SGH-A887 Solstice, SGH-S5230 Star/Tocco Lite, SGH-T749 Highlight/Spark
Sharp: DM002SH, W41SH, W42S, W51SH, W52SH, W61SH

240 x 320
Asus: Galaxy II, P550, M930, P526, P527, P552, P735
Audiovox: CDM-9900
AT&T: 8500, Tilt (8925) & (8925a)
HTC: Tatoo
LG: 3125, CU720 Shine
Motorola: Razor V3, V3xx/xxR, V9, V9x Z9...
Nokia: 6126, 6555, 6650, 6790 Surge, N75
Pantech: Duo, C820 Matrix Pro
Samsung: A717, Sync A707
Sony Ericsson: A100i, A130i, A260, A270, C123/123A, C510a, C702, C902, C903, C905/905a, G502, G700, G900, K770i/770iv, K790, K800,/800i, K810/810i, K850i, M600, M608c, P1i, S500i, S700, S710a, T650i, W518a, W580i, W880,/880i, W890/890i, W900i, W910i, W950/950i, Z750a, W770i

176 x 220
Audiovox: 5600, CDM-8940, CDM-8945, CDM-9500
LG: 535, CU515, MM-535, VX7000, VX8100, VX8600
Motorola: A840, C698p, C975, E770, E815,  i550,  i600, i605, i680, RZR, SLVR, V3r, V330, V540, V551, V710
Samsung: a790, a890, a920, a940, i600, p207, SGH-A177, SGH-A517, SLM (A747), UpStage
Sanyo: 7400, 8300
Sony Ericsson: 750i, F305, K700, K750i, K578c, V600i, V630, W302, W380a/380c/380i, W395, W550c/550i, W600i, W610/610i, W660i, W700, W810/810i, Z610, Z710i, Z800

128 x 160
Audiovox: PM-8920
LG: 1150, 1200, A7110, C2000, CG300, F7200, F9100, L1400, L1400i, VX5300
Motorola: 300, C257, C290, L2, L6, V190, V235, T720, 720i
Nokia: 6061, 6085, 6102, 6102i, 6651
Pantech: C150
Samsung: A117, A127, A437, C417, D347, D407, D357, E316, SPH-M310 (Slash), X426, X507, V206  
Sony Ericsson: F500i, K510, R300, T610, T637, W300i, z310A, z520/520a, Z525, Z600

128 x 128
Audiovox: CDM-8150, CDM-8610VM
LG: CE110, CG180, CG225, C1300i, C1300, C1500, CG225, 4010, 4011, 4015, 4020
Motorola: C168i, V180, C380
Nokia: 2610, 3100, 3120, 3200, 3220, 6030, 6100, 6200, 6230, 6800, 6820, 7210, 9300
Pantech: C3, PG C120, PG C300
Samsung: X427, X427M, X497
Sony Ericsson: J200, J210, J220/220a, J230, J300, Z200, Z300/300a

320 x 240
Blackberry: Curve 8300, 8310, 8700C, 8820
LG: CB630 Invision
Motorola: Karma QA1, Q Global
Nokia:  E62, E71x
Samsung: A827 Access, BlackJack/BlackJack II (i617), SGH-i637 Jack